This is a screenshot of a folder on my computer that is full of new or unused guitar riffs I have written. A few years ago I got into the habit of using the built in camera on my iMac to record myself playing anything that I think has potential to be developed into a song.
This allows me to not only hear the guitar parts, but also see how they are played. If it is something rather complex or crazy fast I play the riff full speed as well as at a slower pace to make sure that down the road I can pinpoint exactly what I was doing at the time.
The oldest unused riff was recorded Thursday, April 2, 2009. The most recent was recorded last night. Currently there are 251 files in this folder. Though the actual number of riffs in here is higher. This is because sometimes I have a few diddies that work well together, so I alternate back and forth between them while recording. I'm guessing that the number of unique guitar parts here is easily over 300.
Occasionally I will also have a drum beat in mind to go along with whatever I am playing. In this case I usually just beatbox it in the same movie clip.