You could play Rock Band or Guitar Hero through your TV speakers, but your classic shredding deserves better. If you don't have your gaming console jacked into your home theater system, try Altec Lansing's Stage-Gig, a 40-watt pignose amp putting out an ear-splitting 100dB through a 1-inch neodymium tweeter and a boom-a-licious 6.5-inch woofer.
Like any good portable speaker/amp, Stage-Gig has standard RCA audio jacks (but no 1/4-inch jack, which makes it tough to plug in a real Les Paul Gibson, Fender Stratocaster or Rickenbacker 12-string) and an independent volume control, a handle and padded corners so you don't hurt yourself, furniture or whomever you accidentally brush up against as you wander.
Stage-Gig is a mono speaker, but you can daisy chain two of them to create a phony stereo plus increase the likelihood of roommates or parents yelling at you to turn that damned thing down and hasten the onset of tinnitus. Altec won't help you avoid either — the Stage-Gig is just $100.