What makes a good bug tracker?

[eluser]CI Evan[/eluser]
I'm sure this is a question that most of us have debated as pretty much every bug track app out there just doesn't quite fit the bill in one way or another, or so it seems from most of the people I've talked to about the subject. Thus, I've started an open source project with the goal of creating a bug tracker that can fit every project but still has significant capabilities. Specifically, I'm looking to take a modular approach to the task at hand so that anyone who has knowledge of PHP could easily extend the app to meet their needs. If I get a strong enough response to this I would certainly consider having additional developers help with the project so please let me know if you are interested.

Meanwhile, I'd like to turn this topic into an open forum discussing what you hate, what you love, and what could be improved about any bug tracking app you've ever used. Any suggestions at all...

[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.