yay!
for me, Youngsta's mix
Dubstep Allstars 2 captures the bare essence of dubstep -- it's meditative, tense, and heavy. lots of DMZ. the set is impeccably mixed so it's a pleasure to listen to, even if there aren't that many tunes.
Tectonic Plates is another good compilation from Pinch's label. Pinch also has an album forthcoming on Planet Mu -- i'm pretty sure it will be excellent.
you could also search for some online mixes: Dubstep Sufferah 1 + 2 by Grievous Angel, Autonomic Computing by Paul Autonomic, and
X Plore H Core or Quantum Lines by Ben UFO (i linked to it in the "other people's mixes" thread).
if you like Burial's swing, you might search for the Horsepower Productions proto-dubstep album
In Fine Style, which represents the late 90s transition out of 2-step and into dark dubby garage.
OH YEAH, and the new 2cd Skull Disco comp is killlllllllllller. wicked eerie & deep tribal bizness from Shackleton (mostly). kind of an anomaly, but essential.....