Do check it out. A Professor at San Diego wanted to check out the right wing meme that Obama is the most left-wing Senator. He did the work and decided to put McCain in the mix too. He found that in the last Congress but one, McCain was he 2nd most right wing in the 109th, and the 5th or 6th most conservative in the 108th. (That's out of 101 total)
Obama wasn't the most liberal.
To check it out: fivethirtyeight.com