Rapid Tab for iOS

Transform audio from your guitar or bass into tablature automatically; you can keep your hands on the instrument instead for scrambling for a pencil and paper every time you figure out a riff from a song, or come up with something on your own. The app also lets you control MIDI synthesizers, and has a full set of tablature editing tools. Export transcriptions to PDF, MIDI, or MusicXML.

Rapid Tab is available in the iTunes store.

The user manual is here.