The non-partisan Wisconsin Democracy Campaign is featured in this story on one of the more unusual aspects of Wisconsin's recall law -- there is no limit on donations (normally its $1,000). As the story notes, the GAB claims it's not a loophole, though that is clearly a generous interpretation. The legislature itself wrote the law, and, as the targets of recalls, they are the prime beneficiaries.
Due to the heightened interest in the recall, it might not make that much of a difference in these races, which have become state-wide (if not national) battles, I have to imagine that the money would come in through third party spending. In other, less exciting races, it might make all the difference in the world. At least we get to see exactly where the money is coming from.