If so, you can buy very inexpensive computer interfaces that allow you to hook your guitar up to a computer and record directly in. 50-100 bucks should set you up.
If not - I use my cell phone alllll the time to put down little ideas and what-not. It works but like you said, you end up with a video as well.
You can always do the old school method of a cheap cassette deck with a built in microphone. haha.
