Yeah, Satanische Vrede ("satanic peace") is pretty great.
They have a new double album coming out in April... there's short video here:
http://vids.myspace.com/index.cfm?fuseaction=vids.individual&videoid=50998 363
('Satan likt mijn hielen' means "Satan licks my heels".)
My other favourite band from Belgium is Alkerdeel, check them out:
http://www.myspace.com/alkerdeel666
Especially "Luizig" really impressed me, 21 minutes of dark sludge doom metal.