Google alerts for Twitter!
You heard right. Sidetrack sends notifications (via email or DM on twitter) whenever someone tweets about your search term.
It began as a Rails Rumble 2010 project. Despite the best efforts of the team, the application was not completed within the 48 hours allotted for the contest. However, since winners never quit and quitters never win, development will continue here for as long as the application proves useful.
We sincerely hope you will consider contributing as we continue to improve and refine it into a useful tool for Twitter users everywhere!