...remastering or remixing your old music.
I've always loved to go, take my old track and upgrade it with new knowledge, new skills and inspirations, because there is something nostalgic about it. You are battling your way throught your own mess that you used to do, but back then it was perfectly normal for you.
This also enables you to clearly see the difference and the progress that you've made ever since you composed that original track.
I'm doing this from time to time, trying to take my old shitmastered tracks and spike them higher with some new material :D
Sometimes it works out and sometimes it doesn't but its still a lot of fun for me and don't get me started on the educational value of these things.
So um yeah, I made this :D http://www.newgrounds.com/audio/listen/521564