I have enjoyed the various series written by
Richard Tuttle, which are available at Fictionwise. I've read every one of his books except the newest which was just released (I've purchased it, but haven't gotten to it yet). They aren't "dark" fantasy, but they are fantasy. They are very-well written and engrossing.
I'm currently enjoying Lawrence Watt-Evans'
Ethshar series of books. Each book is really standalone, the only real connection being that the storeis take place in Ethshar. Again, these aren't "dark" fantasy in the true sense but they are well written and very enjoyable. I've read 6 of the 7 books and will be beginning the seventh tonight.
A third good option is Alastair Archibald's
Chronicles of Grimm Dragonblaster series. I've read all of the books and waiting for the final book to be released in November. Again, they are not "dark" fantasy but they are well written and engrossing.