Amps and Cabs for iPhone
I'm not sure that we've had an actual amp simulator before, but here's one. Here's the app's description:
Ground Up Audio proudly presents Amps & Cabs, the best guitar amplifier and speaker cabinet simulation you’ve ever laid eyes on. This sweet sounding guitar app packs a selection of hot amps and cabs, so you can rock huge sounds anytime you want and everywhere you go. Amps & Cabs comes preloaded with three (3) different types of amps and three (3) different sizes of cabinets to make 9 different combinations. Build a guitar stack that fits your style and customize the settings to create the guitar tones you’ve been dreaming about.
Simply swipe left or right on the amps and cabs to mix and match them. To adjust a setting, tap a knob and use the pop-up slider to dial in the right amount. When you want to come back later, everything stays right where you left it - just like a real amp.
Amps & Cabs at the app store: