At work we use a product called Skinnyboard. It has a ton of great features, like:
- Support for Sprints and Product Backlogs
- Sprint tracking via stories/tasks
- Individual task history
- Sprint/Product Backlog burndown, to see projected finish dates, etc.
It's free to try, which gives you (I believe) one board. After that you have to pay though, but it's a great product and definitely worth it.
It's simple, visually appealing, and only has what you need. In my opinion, it's like the Basecamp of SCRUM tools.