There's a whole boatload of insanely talented fretless death metal bassists... most were probably inspired by Steve Di Giorgio who was one of the first to bring fretless into that style of music when he joined the band with the actual name DEATH when they got into their super technical phase.
Probably one of the most famous current bands in this genre with a fretless player is Obscura... here's one of their videos:
http://www.youtube.com/watch?v=mesr2siegRgAlthough I did the metal thing when I lived in the Bay Area fairly successfully, my tastes never quite went too far in this direction... however, I respect their abilities immensely. They're borderline athletes on their instruments.