Free Trouble Ticketing System

[Zxian]

I'm administering a number of computer systems, and I think that my life would be a lot easier if I had a web-based ticketing system for users to contact me with. Does anyone know of any good ones that I could use? PHP/MySQL based would be ideal, since I've already got that up and running.

[tain]

I don't have experience with any of the free ones, but you can find a decent list here. The first resuslts, in yellow, are sponsored.