We are in the continuous process of adopting Agile. It's been (so far) a 18 month work in progress. We started w/ few tools other than pen and paper 1.0 (a co-worker's term). After a bit
we (re)introduced a feature/defect tracking tool we already had.
The tool we use is Test Track. It's 'ok'. I haven't had a lot of experience w/ others, so I can compare. It allows for release/iteration planning for tasks/defects. I would encourage you to look at several before deciding.
Before we started utilizing, we used index cards and pencils and white-board. This really is a good way to get started as the upfront cost is minimal.
Things that really work:
- Daily stand-up at 8:45 sharp. 10 Devs are done in about 8-10 minutes. Took about 6-8 weeks to get it from 20-ish to that time.
- Release cycles of 6 weeks with 3 2-week iterations.
- Having a product back-log of tasks and bugs estimated out.
- Printing a daily burn down to make velocity visible. When used as motivator, it's great.
- Getting management to realize w/ our shop, each dev gets 6 hours of work in a day. The other 2 are meetings, fires, etc...
Things we are improving on:
- Continuous improvement.
- Retrospectives at the end of iteration and/or releases.
- Planning can be difficult for the array of products our company works on. It's hard to devote the 1/2 day or day per team to plan tasks for the coming iteration.
[Edit] I consider daily routine (stand-ups, etc...) to be 'tools' when considering agile as it provides a foundation for other, more traditional tools.