The main goal of this question is to generate a list of reasons why you should use bug tracking software.
I have some of the basics
I know there are other, probably better reasons, so what are they?
Bug tracking software is also useful for setting milestones and accepting feature requests.
Collaborating with team members to assign responsibility, track progress, get estimates and liaise with clients is a great function of many bug tracking products.
Customer relations
Tracking bugs might be good for internal purposes it also gives a platform for customers to vent frustrations straight after finding bugs without said frustrations bottling up inside them to a point of no return. It also boosts a company profile if you offer such services to your clients.
While others have given the enterprisey/servicey answer, the reason I have used a bug tracking software in my personal project is simply because to have something to taunt me. Each of the tickets remind me that there's still much to do, and it's not time to quit, because the software isn't "complete."
Oh, and it beats post-its and in-code comments as todo reminders.
Stats, Accountability, Progress Tracking, Automation.
We use our bug databases to track stats such as:
Other nice bits of data you can get out of your DB:
Also, without a bug database, where do you store automated bug reports? Any project with some reach will generate thousands of user bug reports / automated crash reports. Automatically stuff this stuff into your database so you're not spending tons of time juggling emails.
Another minor benefit of bug tracking. When a user reports a problem, you can search the bug database to see whether it's a known problem in an unusual guise, or a completely new problem. Raymond Chen has an example in this story.
It's a great way for feedback from users. They report what they really find important about your software (not always exactly what you would).
Besides, it can be used for automating things such as Known Bugs, Roadmap, managing responsibilities etc. And a living bug database means the software is being actively developed, which definitely enhances the image of a project.
What is the alternative you plan to use? E-mail? A white board? Your short-term memory? It will help if you compare with the alternative rather than in a vacuum.
In addition to those benefits which you have noted, using bug tracking software allows for a shared sense of the product.
I can't imagine working on a non-trivial piece of software without some form of bug tracking.
The better bug trackers integrate nicely with your version control too, and they really complement each other. VC commit logs tell you who and what, bug tracker comments tell you why.
A good bugtracker really fosters cooperation between testing and debugging too, and it makes it much easier to "throw" bugs from one developer to another because the information is all there instead of in a hundred odd little emails and post-it notes.
I use and recommend Redmine by the way .. very nice CVS and Subversion integration.
Now that is clear why, we should talk about which one!!!!
I recommend Assembla's bug tracking tool. It's really easy to use (as easy as using gmail stars system) and has a lot of cool features!
[Desiree] - I can't agree with you more. I love Assembla.com and Bontq.com, they're just awesome.