Any recommendations for one? I would like it to have a "black hole" reverb of some kind.

I've heard good things about BOSS Multi-Effects processors. They also come with COSM amp modelling.

Here, you can find something at this site: http://bossus.com

There are easy-to-build circuitry that you can make your self, but I strongly recommend analogue gear and not the digital stuff (neither HQ stuff)...
But It goes on your own... What genre you use to play?

I have a Line 6 floor pod and love it. It's has all the shred my JCM900 had, but I can get that same "full blast" sound without rattling the windows. I guess they quit making the one I have, but this seems to be the replacement:

http://www.guitarcenter.com/Line-6-Floo ... 1172343.gc

It can be th best digital processor, the most powerfull multifx ever built, but it won't sound as drivefull as a couple of hot tubes amplifier... from there, you know that cant sound as good as you think you can from digital platforms, but... Can you??? Really?? Do you hear what you want, or want what you hear??