- sean malone of cynic and self titled project (though the latter is a much more experimental affair)
- jeroen paul thesseling played on pestilence's spheres album... he also has flamenco bass work with a dutch flamenco gu*tar player named "el periquin"
- Tyr's fretless work on Borknagar's Empiricism is absolutely beautiful (for a lack of a better term)
- Steve Digiorgio, who is one of the artists with most projects i've ever heard of (next to gene hoglan and dan swäno

) plays awesome fretless in testament's the gathering and quo vadis' defiant imagination (i can't stress this enough:
GET THIS ALBUM!!!!)