Demonstrating that I try to be even-handed:
Hillary Clinton has been criticised several times (including by the eloquent Lessig) of cozying up to special interest groups for money (via PACs and similar). The evidence, however, suggests that none of the candidates get very much of their money from PACs. In Senator Clinton's case it comes to about one percent of her 2007 Presidential campaign funding. Instead, she (and essentially every other candidate) get all of their money from individual donors (with the exception of the Mittster, who blew $35 million of his own dough; should've just put it all on black).
So I don't get it: where's all this evil special interest money that people are talking about? The more interesting data is the sizes of donations to each candidate. Instead of working on my thesis this afternoon, I downloaded the data for 2007 from the FEC and found the following distributions of donation size (money coming from private individuals only):
This shows a substantial difference in the ways in which the two candidates have raised roughly $100M each. A third of Obama's money has come from donors contributing less than $200 each, which means that he has an incredibly broad fundraising base compared to Clinton, who raised nearly two-thirds of her funding from individuals who donated the maximum allowable by law ($2300 per campaign, per year). This is perhaps especially interesting given that she is generally reckoned to appeal to lower- and middle-class voters. The data suggests this not to be the case when it comes to opening pocketbooks, since the sub-$200 are presumably mostly from these groups.
Also of interest is the tendency for people to donate an "even" $500 or $1000 regardless of whom they support.
Anyway, I should probably do some actual work now, although the FEC files are fascinating, and include full records of every donation of more than $200 to every candidate for public office. A man named George Clooney, from LA, for instance, donated the legal maximum of $2300 to "Obama for America" last April.