New Webjay playlist: Punk Voter - tracks from bands that are listed as members at punkvoter.com. To be able to vote in the US, you need to be registered with your state, which means downloading this 1-page form (PDF), filling it in, and mailing it to the appropriate address found at the end of the PDF.
After a while I got bored of searching record label sites for MP3s, so after the first few the bands only got included if they had MP3s linked from their own sites (including those that had to be packet-sniffed out from under Flash front-ends). Full credit to Bracket and Trans Am for having the only decent (almost completely) HTML-based sites. Interestingly, NOFX were the only band to have a .org.
Many of the tracks included aren't particularly political - for whatever reason, the bands had chosen different songs to put on their sites. There are two compilations on Fat Wreck Chords though, Rock Against Bush Vol I and Vol II.