Best music-related iPhone/iPod Touch apps?

[bassman1185]

I thought it might be cool to tip each other off to cool music-related applications. Here are a few of my favorites so far:

BeBot Robot Synth - $1.99
Think a basic Korg Kaoscillator. Weird pitch-bending synth with a lot of really cool functions. Ridiculously fun to play around with, and VERY cool to hook up to your bass rig or a large PA system.

PianoFly Synth - $1.99
Fairly full-featured synth with three oscilators, each with a selectable wave form, pitch adjustability and envelope controls. Lots of weird sounds, and you can save tons of presets.

Studio Six Digital RTA - $9.99
Not so much a music-making tool, but a really useful gadget for analyzing rooms that you're working in, for EQing out feedback, or for seeing how your band's sound "looks" to help you fill in the proper frequencies. Has a full 1/3 octave analysis readout, pink noise generator, selectable noise curve overlays and more. The downside of this is that you need to get an external mic if you're using it with an iPod Touch, which compromises the accuracy of the analysis. Studio Six is coming out with a new mic that will plug directly into the port on the iPhone/iPod Touch for a more accurate readout and higher SPL ratings.