What makes a good bug tracker?

[eluser]DPrevite[/eluser]
I've been looking at bug trackers for a while now, but there aren't many options (that I've found) for bug trackers written in PHP.

Trac looks pretty decent. I don't think a bug tracker that doesn't work with our version control will ever be useful. However, Trac is written in Python, which I just don't know a single thing about. Changes would also be difficult to make since I work in an all PHP shop.

There are some good hosted bug tracking systems, but for our purposes it would have to be running on our intranet.

I've been looking into making my own in CodeIgniter for a while, and have made a little progress, so if you want some more feedback or some help, let me know.