Guitar gadgets: Line 6 'Backtrack'
An inline memory device that records your guitar playing as you go, with the ability to mark the bits (and I do mean bits) you want to keep and dump to your PC. There's a microphone option, too. Always on, BackTrack begins recording as soon as it detects a signal. Just plug into the quiet 1/4-inch input and start playing. And use the 1/4-inch output for immediate playback. Just set it and forget it for total inspiration control. Pressing the “Mark” button designates what you just played as special and separates it for easy review. The Forward and Reverse buttons provide instant recall of marked and non-marked ideas. It has a Gig of on-board flash RAM.
Alternatively you could also just run your guitar through your PC (using iAxe or some other USB interface) and save as you go, but that's a heftier option, especially if you are playing away from home.