I'll jump in and say the Echolution mentioned by Glocke is pretty incredible. The online tour there will probably tell you more about it than I could. I'll just say it works as advertised, sounds great, and doesn't take any sound away from the bass (edited to add: or guitar... wait, there are guitar players here? Guess I haven't been paying attention....)
[I always feel obligated to state that the Pigtronix dude is a buddy and former bandmate of mine, although if the pedal was no good I wouldn't lie.]
(Message edited by jack on August 10, 2009)