I love Sikuli! What I like most is that the source code contains pictures! Since I have a background in visual programming and programming languages based on comic strips, one might have guessed that I would fall for Sikuli :-) Even better, the programming language is Python (Jython), which makes for really clean code.
Now, what is Sikuli? It is a tool for scripting user interfaces, and it is based on matching images (for example an image of a button in the ui). I introduced Sikuli to a client the other day, and now they are using it to create automated ui tests for a web application.
I have one hint, importing modules with Python's standard import statement does not work, instead use execfile to load your Python modules (see link below).