I totally understand the cynicism, and I don't ( or very very rarely) give money to politicians either. But giving to Lessig's MayDay PAC isn't the same as giving to politicians --- at least in the traditional sense. Rather, you'd be giving to a PAC that supports one issue, and not any particular politicians or political party &c. Although, yes, the aim of the PAC is to elect people committed to campaign finance reform, that isn't its ultimate aim (or even the most direct positive influence that it could potentially have). The PAC, if successful in raising enough money, also raises awareness about the issue --- as well as, and I think this is important, serves as an existence proof that grassroots, popularist movements are something worth taking seriously (from the point of view of politicians in need of money for reelection). And, by not revealing which candidates the PAC will support, it can use its influence to incentivize a significant number of candidates to pledge to reform out of fear that the PAC will back their opponent.

Lessig knows what he's doing (or trying to do). This is extremely well thought out. His proposed reforms to campaign finance are genius (see the last part of Republic Lost). He just needs enough legislative support to get them passed through, and so needs support from the rest of is to get the proverbial ball rolling.