Creating or Inventing a device

Maybe a wishful thinking question, but it would change a lot of songs.
On a sunny day, you play a super nice lick, with a little solo, and the song is not bad at all.
What can you do, because a little bit later, you've lost your concentration by picking up the telephone, = realistic example.
We all are aware that one day you play twice as good as another day, but the problem is there arriving slowly, that you CAN'T remember at all, the fantastic chord and lick, you oplayed an hour ago.
There are these days enough electronic devices on the market, recording at the spot what you are playing. I don't find a musician who plus his guitar in the recorder ( a splendid device is Boss Micro MR, with a PDA size, and having 4 tracks, and 32 (?) virtual tracks, with build in rhythm patterns, (drum and bass loops), I just saw 300 different drum patterns, YOUR OWN POCKET STUDIO. You can also buy a device with 8, 12 tracks like edirol, tascam, boss.
The Zoom H4, deserves a special place, having two super mics, and this ZOOM H4 has also a lot of other capacities like a 4-track recording mode for easy-to-use mobile multi-track recording. and using a 2 Gb card, you can record more than 300 hours and put it on your PC, WHAT I DON'T KNOW IS IF IT HAS ALSO RHYTH PATTERNS, LIKE OUR BOSS MICRO MR.
Going back to the topic, there is no word about acoustic guitars.
To keep your fantastic chord-lick-solo in mind, I should love to have a very small device, with a 2 Gb capacity of storage. A device, you can keep in your pocket, and when you play, the only thing you have to do is, stick it on your guitar, and it records, using the vibration of your instrument, which makes it possible to record every lick like you played it before you had to answer the phone, and you will find that nice melody back, as you played it.
I am talking about a real small device, that you can stick on every guitar you want, acoustic, or electric, having a diameter of 4-5 cm, and a hight between 5-10 mm. No other effects on it, just picking up the sound of the chords you play, add a little jack, and the other side of the chord having an USB, with a second plug in, and at the end a thiny little kind of headset to listen, what you played two hours ago. Almost every musician has got this bad expeience of the lost brilliant tune. So, do you know:
- if such a thing is available on the market?
- if this would be of a certain value?
- how to create a device like this?
I don't think that the concept is ridiculous, I tried to explain, as much as possible, and now I hope to get responses from fellow chordians, or at least what they think about it. SO, A DEVICE AS I DESCRIBED, PURPOSE: FINDING BACK WHAT YOU WERE PLAYING BUT YOU FORGOT.
The other small pocket studios: is there somebody, who is familiar with these items, and the concept I just described. This was a real hard one, to write.