*revives thread*
Well, I discovered AudioStreet about a week ago, and am officially addicted to it. They have a heck of a lot of unknown bands, and here are some of my favorites (plus some random non-AudioStreet ones I found recently):
Argoth - epic instrumental metal or something like that
Brooke Annibale - generic pop-rock
Crimson Tears - metal
Detached - instrumental metal
Di Sheldon - pop-rock
Epic (different from Epica) - instrumental metal, I think
Ex-Therior - operatic metal, sorta
Hanging Doll - gothic metal
Holly Brook - sort of folk-rock, a bit Joni Mitchell-esque
Indigo Child - symphonic metal, I think
Kamelot - ok, they're not unknown

They were unknown to ME a month ago, though. Am very proud that I found out about them with only Wikipedia's help.
Liv Kristine - she's the singer-person from Leaves' Eyes, but she's also done some solo work that's not bad at all.
Lyriel - Celtic-ish stuff
Maren Ord - pop-rock
Power Quest - probably another band everyone on the forum but me has heard of, but I just found them today. Power metal, obviously.
Rayna - acoustic folk-rock
Serena Lauren - pop-rock
Trish Murphy - folk-country
And you've all probably heard of Visions of Atlantis, but they're kinda unknown to me. Go AudioStreet!