All tracks on Aaron Neville's My Greatest Gift have become streamable, bringing a couple of my favourites with them: Hercules and Tell It Like It Is.
I think, first heard Amy Winehouse's Rehab on Later...with Jools Holland, now it's streamable :)
Dropping the mood, for a couple of tracks: B.B. King's The Thrill Is Gone and Bruce Springsteen's Streets of Philadelphia (sacrilegious to some, I'm sure, but one of the few of The Boss's tracks I like).
Serrado is the track that first got me into Djavan, when it appeared in Gilles Peterson's Gilles Peterson in Brazil selection. The track's a luscious latin swing fest', the vocal gymnastics are amazing, yet so natural - Prepare to dance, this track's a joy!
Four Tet's She Moves She suffered from misassigned audio for a while - now proper stuff streams again :)