Posted this at BYOC as well, but I thought you guys might appreciate the info as well:
I just got my iPhone on Monday, and I've been pretty busy the last couple days. But this afternoon I had a bit of time to play around with some apps.
I picked up a chord finder, some weather apps, a great little "Craft Beer Finder", and all that normal crap. And then I saw iShred. Had to have it, as it was only $5.
I also got the Guitar app from the same company (also $5), and it's really similar but with acoustic guitar tones (6- and 12-string sounds, as well as nylon).
But iShred is a electric guitar junkie's app. It's got a nice pedal board setup with several pedal models (flanger, chorus, delay, tremolo, and a couple others). There is even a three-position pickup selector switch.
It also has recording capabilities, and you can loop your recording and play over it. And the recordings you save are accessible over wifi from any computer on the local network.
There are several songs already built in (chord progressions are mapped out and effects are set), and you can make your own. You can also save pedal board setups as well for use in any song.
I haven't even scratched the surface of this yet, and already I'm blown away. The sound quality is excellent.
I did a quick little demo with clean electric guitar, delay, and some chorus. Took me all of 5 minutes to download the app, figure out how it worked, record a clip, and then get it on my computer. Here's the demo:
http://www.archive.org/details/IshredDemo
The same company (Frontier Design Group) also has a free app called iShred Live, which basically has the same function as a Line6 Micro Pod. You have to buy a special cable to plug your guitar in, but I think it's something I'll end up getting sooner rather than later. Having a mobile amp emulator and pedal board in your phone is pretty awesome. Great for traveling.
They also make a Piano app, a theremin, and several other oddities.