Felt like resurrecting a thread for funsies...
I bought a used Thungergun almost two years ago from dude who runs Abominable Electronics. I got a good deal on it, but I had to have the nut repaired (thing is stuck real tight, so fixed it with some compound... it's fine). He was playing lots of doom on it with really fat gauge strings and routed out the E slot on the nut. Fun times. Anyway, this bass replaced my Blacktop Precision Bass as my main gigging bass. I thought the P was very sufficiently growly and was pleasantly surprised that the Thundergun is even gnarlier.
I play in a loud, fuzzed out rock band and play with a pick

D). I keep my pickups blended fairly even, with a very slight twist towards the neck pup, and also keep my tone at about 90% high. I'm using half rounds and I get lots of boom in the low end and real fantastic "clangy" mid-highs. You can really go hard on this bass if you want. It will take the abuse, yet it's probably suitable for any style of music (but yeah... rock/metal especially).
This thing is mean and nasty, and also beautiful and well-constructed. Also, they're only about $800-900 new. If you can manage to get one for around $600 like I did, you would be in luck.