A series of compilations on the German record label
Mille Plateaux (which is something that ideath had had listed she was going to node, but now she doesn't--but it still isn't). This series includes music by artists like Panacea, Alec Empire, DJ Spooky (great writeup by eclip5e, btw), Techno Animal (which features one of the members of Godflesh, & DJ Vadim. There are currently 6 volumes, I recommend 'em all if you like these folks or the following description...
What it is, is electronic music with an aggro streak and with foundations in and references to industrial music, hip-hop, dub, and, um, Satan (not really). Illbient is definitely an applicable term to some of it.
Increasingly, also references to noise, or where noise (as in hell is now love's definition) meets ambient maybe. But that's a story for another node about the Modulations & Transformations series on Mille Plateaux, which I'll have to writeup sometime soon.
This was my first writeup (though it's not a first writeup)--wheeeeee!