You might want to start with the projects that users have said work for change in particular ways (rather than simply being about "raising awareness")—and, for a little more focus, the curated section of particularly effective actions. Just go to Actipedia and click on the "How it works" menu—and judge for yourself whether projects actually do what they're said to!

Actipedia is a joint project of the Yes Men and the Center for Artistic Activism.