The Royal Academy of Bards -- Meant as Xena Fanfic, but you'll be surprised at the number of the most popular lesfic authors and their works that you will find on this site. Some of them are Radclyffe (The Honor Series, Tomorrow's Promise and many others), Ali Vali, Susan X Meagher (I Found My Heart in San Francisco Series is still up), Blayne Cooper, LJ Maas (None So Blind)
The Athenaeum -- More Xena fanfic, but with authors like Ann McMan (you might even find her awesome Jericho here), Melissa Good, K.E. Lane (writing as dabkey -- you'll find the fantastic And Playing the Role of Herself here)
A Journey of Soulmates -- The best Xena fanfic...plus more.
Free Lesbian Fiction Books on Amazon (Kindle) -- Lots of bestselling authors offer free reads -- don't miss them.
Free Lesbian Romance Books on Amazon (Kindle) -- You never know which gem you might get here for free...
Free Books on Smashwords -- You just might stumble upon established authors you've always wanted to read...
Literotica -- Has some surprisingly great stories