On the project that I'm working on, we are currently tracking our sprints with index cards (on a wall gantt) and by daily/sprint/release burndowns in a spreadsheet. The wall gantt is the tracking that is used for our day-to-day tasks and the spreadsheet is used more as a communication tool for our external stakeholders.
Our team has recently run across some issues with a few third-party software packages that have impacted our velocity and required some additional tasks. As part of the on-site team, my visibility has mostly been with the wall gantt. I've noticed that our velocity has taken a hit, but I wasn't sure how our velocity had trended over the release as a whole.
I recently ran across sparklines and was interested in using them to take a look at our velocity. I was extremely impressed by how much information could be viewed in a short space.

It's fairly obvious where the trashing started (around sprint 10). The sparkline shows a daily story-point burndown inside of each sprint. The high and low points of work remaining for each sprint are shown through the different colors. For the spreadsheet, I used the free Bissantz tool (thanks guys).
I'm looking forward to picking up Beautiful Evidence by Edward Tufte and reading about more visualization patterns. Reading his work is always extremely insightful.