We released the first version of the Pivotal Tracker API a couple of months ago, and already there is a growing list of useful third-party tools out there:
Synchronize stories in Pivotal Tracker with Cucumber features. If you haven’t heard of it yet, Cucumber is a really cool app that can execute plain-text documents as automated functional tests.
There are more, most of them live in GitHub:
If you have written something you’d like to share, or know of other useful tools, let us know! Also, we’re planning on making the API better, and would love your feedback.