Simply subscribe to author Doug Clegg's e-mail newsletter and get a chance at winning a free Kindle or Nook; details and newsletter sign-up are at his web site.
Did you know that author Larissa Ione posts free reads on her web site? The latest is a free short story featuring characters from her Demonica series.
For you Kindle users, author John Kao has his nonfic guide Clearing the Mind for Creativity up for free download on Amazon here.
Author Rudy Rucker has posted free .pdf and .rtf versions of The Ware Tetralogy for downloading under creative commons here (not sure what this is about, exactly, as the author's description isn't too clear. Might appeal to the zombie lovers.)
For the next week or so author Shiloh Walker is having a contest to give away an ARC of her upcoming release Veil of Shadows; all you have to do to enter is leave a comment telling her why you should win it (you'll have stiff competition for this one; I just read through the entries that have posted and they're all pretty terrific.)