Lurker here (and thank you ladies for all the freebie links you provide!) but here are my other sources for freebies...
http://ereaderlove.com/ and Digital Book Today (both also send daily emails)
Mixed genre, and apologies if they are full of affiliate links, I'm a Kindle newb and don't actually know what an affiliate link looks like... or how one makes money off free books?!
I've tried a few searches, both by price and using terms like "save 100%" etc. - but wow, you need a lot of time to sift through it all!