Just when you thought you had the shadowy world of super PACs figured out, here comes a new twist: Three big Democratic super PACs -- formed to support President Barack Obama, and House and Senate Democrats -- are banding together to form the first ever joint fundraising super PAC.

The three, which registered their joint committee with the Federal Election Commission last week, are among the largest super PACs, in terms of contributions to their committees. They've raised a combined $10 million for the 2012 election so far. But that figure looks less impressive when compared with the haul of some ...