I didn't have time to read all the replies, but these are the links I use to check freebies, sorry if some have already been posted. The first 3 are my favorite and 'go to daily' sites. I hope I'm not breaking any rules for posting, I have no affiliation with any of these sites, just posting the ones I use the most and trying to be helpful.
Amazon, top 100 bestsellers and freebies, updated hourly:
http://www.amazon.com/gp/bestsellers...d_dp_ts_kinc_1
This one is great because you can sort by date added/genre etc:
http://www.freereadfeed.com/
This one is also really good for sorting by genre, even format, etc.
http://www.ereaderperks.com/
This one gets updated sometimes twice a day, good for a few freebies and hot deals daily
http://www.pixelofink.com/
This one just gives a few daily, usually a freebie and couple of hot deals:
http://www.acheapromance.com/
This is just for kobo, and doesn't get updated daily, but I have gotten a few great freebies/deals occasionally:
http://epubdeals.com/