Brain Drill has a bass solo in a lot of their songs. I'm not really a fan of the band, but Jeff Hughell is a fuckin intense bassist. Also, maybe not many bass solos, but the bass in these bands are pretty prominent to the point where it is the reason I recently picked up bass (I've been playing guitar for a long time now): Atheist, Augury, Obscura, Behold...the Arctopus, Blotted Science, Spastic Ink, Necrophagist, Gordian Knot, Spiral Architect, Gorguts, ect. I don't really even listen to music that doesn't have highly audible technical bass lines anymore.