EXS 24 Logic Sampler Users Group

Sascha is right on about Absynth. It not only has great pads, but 
lots of highly evocative basses, ethnic sounds, etc. Some are so 
complex and evolving, that you wonder how they did them. Kinda of 
like the Korg Wavestation or Waldorf Wave, but way beyond and not 
dated. The programmability is awesome and you can tweak away for 
days to create endless new sounds. The new Absynth II is probably 
even better.