I've always found the sounds that Brian Ritchie of The Violent Femmes was able to make with his Bass to be incredible...and he seems to be the only bassist in the world not yet mentioned in this thread
Naturally as a Canadian I am partial to Geddy Lee, and as a DMB hippie I am quite fond of Victor Wooten as well. Has anyone ever heard Victor's harmonic only version of Amazing Grace? It sounds just like the tune but I think you need to understand just what stringed instrument harmonics are to really appreciate the genious.
Also for what it's worth, I've always thought flea was quite special. Especially after the video where they show him plucking away at high tension electrical lines....that was freaking neat!!!!
-bear