Ah, the Rus discussion again. Let me just begin with that I logically can't have a nationalist influence on this one, as I'm no a descendant of those Swedes who lived in the period.
As someone reacted heavily when someone else used the word Russia for the area I'll clarify a bit: I will use 'Russia' to describe the area that is modernday cis-Uralian Russia. The reason is that there are no other good term to use. I suppose I could use Gárþariki or Greater Sweden, as these are two contemporary names, but I'll refrain from that as it might cause confusion. So Russia it is.
and so on, but to me it doesn't seem to be too persuasive, since we can create the analogous reversed test - and Swedish Helgi will stand for Russian Oleg and so on, but this doesn't give the right to tell that Swedish kingdom was founded by Slavs, right?
You can't create an analogous reversed set, at least not if you want to make the linguists believe in you. As other said, there are several other Slavic names that have been adopted by the Scandinavians, but Helgi and Ingvar are not among them. The reason is simply that the names are older and appears among tribes not in contacts with the Slavs. Further, take for example Ingvar. Ingvar is without any doubt whatsoever a Scandinavian/Germanic name. It is a compound of Ingr and varjr, the first a god, the second meaning warrior. These parts are present in a numerous other names (Ingolfr, Ingjaldr, Óttvar etc), making it somewhat nonsensical to claim this is a Slavic name.
However, this of course does not mean that Scandinavians founded Russia, just that there were contacts between the peoples, probably including intermarriage.
Conrad can you explain to me why in Kievan Rus - two names Igor and Ingvar' were used if you say that Igor is just Slavic form of Ingvar, why Slavs needed two names to denote one - and by the way note that they called Ingvar' Russian princes?
I can explain. This is a very common happening with new names. I'll take a Scandinavian example, the name Katharina. This name was introduced into the North during the Middle Ages, and it was adopted in its original form as well as in many local interpretations (Katarina, Kajsa, Karin, Katrin, Karina etc etc). There are many more examples, but I don't think it should be necessary to post more. I think the point has been made already.
Then what i doubt about is Ruotsi and Varangians - they are mentioned in manuscripts unequally, that is Varangians are mentioned more frequently than Rus' - let's assume this is a tribe or something, as you know each invader leaves some traces by which you can say that he was here (see Viking invasion to Angslo-Saxon Britain) - then why no traces of the word Varangians can be found linguistically in Russia, the place where they lived for so much time? - Only one place can be mentioned: Varegovo (Varyagovo) tiny city near Yaroslavl'?
Well, the situation is very different. The Anglo-Saxons and the Vikings understood each other's languages quite well and the new settlements could easily be adopted by the Angles and Saxons. Also, the pattern is quite different too. In Britain, the Scandinavians often founded completely new towns when they settled - in Russia they often made a settlement in conjunction with an older one (for example the Scandinavian "village" in Kiev). Thus no reason to give new names. The situation was the same in Normandy where the Scandinavians settled in older towns, and within three generations there language was gone, leaving a few Scandinavian names (Guilaume/William among them). There were Scandinavian names on a few towns, though, for example Novgorod was known as Holmgård (Island town), and the Scandinavian town/trading station at Staraja Ladoga was known as Aldeigjuborg. You must remember that the Scandinavians were very few in numbers and were assimilated more or less fast, just as in Normandy, Ireland or anyplace else. It took longer time and left more traces in Britain of the simple reasons that the Scandinavians were many more and that they could continue speaking their own language.
Moreover, if there really was some Swedish tribe called Rus' - Ruzzi - 'Ruotsi and so on - where are the traces of it in Sweden? Cities? Archeological findings? Old weapons, houses, boats? Manuscripts? Manuscripts of Swedish authors?
This is not the issue, you have misunderstood it. The issue is not whether there were a Swedish tribe called Rus or not, but if the Swedes were called Rus. More on that later.
Now, let me tell you my stance. I do not doubt that the Swedes were travelling through Russia- mostly as merchants. Archaeological evidence show us Scandinavian settlements in various places - Novgorod, Staraja Ladoga, Kiev etc - and written sources makes it unquestionable that the Swedes travelled through the lands as Vikings or as merchants. Now, did the Swedes create Russia? I don't know, and I do not expect I ever will. There is no doubt that there were some influence, but there is no reason to swallow everything by Nestor. Rörik is indeed a Scandinavian name and he is said to be from Scandinavia. What I don't understand is why so many Russians react so negatively one this one. There is really no reason, it happened everywhere, everytime. The current Swedish dynasty is French, the British German. Nobody cares about that. I see no reason to blindly believe that the Slavs were so illiterate (well, literally theysurely were, just as the rest of the world) and stupid that they had to call from foreign help to stabilize the land. I do believe Rörik was a Swede though, and that he did take control over Novgorod one way or another. I would certainly not draw the conclusion that "thus the Swedes founded Russia", just as little I'd say the French founded Britain when Wilhelm the Conqueror landed in 1066. There is no reason to get pissed and kill each other about the degree of influence. There is no way whatsoever we will know anyway (as backward time travels are impossible

).
About Chimaira's reply about Russians founding Sweden:
Yeah, according to Snorri Sturlusson, the Icelander who wrote down the Scandinavian mythology. The Swedish kingdom was founded by Odin from the area around Don in southern Russia.
The famous Norwegian Thor Heyerdahl (Kon-Tiki, Ra, etc.) actually made excavations in Azov before he died (quite recently) to prove that Sweden was founded by people from present day Russia.
The kingdom Sweden was founded by people from outside. The land was covered of ice till as early as 13,000 years ago, and there has been several invasion waves since then. That said, Heyerdahl are known for his extravagant theories, and this is no exception. For the record, the excavations in Azov were interesting, but nothing was found that could proove his theories. When Snorri wrote this down, the stories had been around as oral tradition for supposedly 6-800 years before he wrote them down - which does not mean that the core is untrue. I'll leave the issue open, there is very possible that of an Odin from abroad somehow dfounded the Ynglinga dynasty (in that case he would have been Turkic though, not Slavic).
Now to the names, Rus and varyag.
I won't dig deap into the etymology, as that have been made already, I'll just say a note on Roslagen (mentioned by Johan).
Roslagen is _today_ a part of the archipelago, but this has not always been the case. The etymology is not completely known, but it's supposed to have something to do with roþr, 'to row' or something you row. Anyway, the oldest written source of the name is from a runestone 1071, but the name and region is most surely much older. The area was earlier known as Roden (or different similar forms), and during the Viking age is consisted of the coastal part of the Swedish kingdom, from modernday Gävle in the North, and maybe as far south as St Anna's archipelago. This was the area from which all Swedish Viking, merchant or other expeditions were sent out and is the supposed root of the Finnish name of Sweden - Ruotsi. The people in the area today is called rospiggar, which is a derivative of rosbyggjar - people of Ros. The ros where Swedes though, they were not a tribe on it's own.
Let's use logic instead. Arab and Greek sources tells us about the Rus, travelling on the Russian rivers. Due to numerous things, I have no doubt these people were Scandinavian (Fahdlan, Rus' names on the cataracts, the Rus traveller who was a Swede, etc, for details please ask). And all other things excluded - if the Swedes were not called Rus, why were they not mentioned _anywere_ by the Arabs or Byzantines when we know that they were frequently travelling the rivers. Why Rus, and not Swedes? Well, it is most probable the people from Roden referred to themselves as rosbyggjar (or whatever contemporary term) above Swedes, just as people centuries later still identified themselves with the province first, and not the country. Remember, Sweden was a very decentralized nation - rather a federation of independent states with their own laws until centuries later (oversimplification, but anyway). However, I have not excluded the possibility that the Arabian writers used the name on _all_ travellers they met on the rivers and trading posts, Scandinavian or Slavic. People seem to see it in black and white; either they were Swedes or Slavs, either the Swedes founded Russia, or the Slavs did. Personally, I think it's something in between.
This is what i will call the extreme version of Norman Theory or idea of Greater Sweden
Funny, you do know that Russia was known to the Scandinavians as 'Greater Sweden' during the Viking Age, don't you?


Edit: just saw that that had already been mentioned