I just used a feature of Rake that is not available in any other build tool that I know. Namely, I added an action to an existing task1. This feature allows you to extend the behavior of a task that you do directly own. Say for example, ones defined by the framework you are using.
Rake is neat even if you don’t use Ruby or RoR as your main language; see Martin Fowler’s excellent intro if you don’t know it yet.