There are two things I heard, one yesterday, that I have been meaning to look up. One was a rumor that Obama had a history of recording a 'Present' vote rather than actually taking a stand on an issue, and the other was mentioned on NPR yesterday about Ron Paul's past history of possible racism. I found a few things this morning that I will have to read in more detail later tonight, but on the first charge against Obama, I do see a lot of No Votes on his record.
From Project Vote Smart
http://votesmart.org/voting_category.php?can_id=9490 you can see a wide sample of his voting record. Also an article about it from the New York times
http://www.nytimes.com/2007/12/20/us/politics/20obama.html?_r=1&oref=sloginAnd this one is a bit trickier about Ron Paul. He denies writing the articles, but it's publised under his name, back in the 90's. This was reported in The New Republic also.
http://www.cnn.com/2008/POLITICS/01/10/paul.newsletters/?iref=mpstoryviewAgain, I don't have time to read it all now, but you might. I'll have to get back to it later. I have almost a month before Super Tuesday.