According to HPANA (a Harry Potter fansite praised by JK Rowling herself) as well as a few other sources, Alan Rickman (Professor Severus Snape, of course) and Warwick Davis (Professor Flitwick) are among the cast for the movie Hitchhiker's Guide to the Galaxy, which is based from the Douglas Adams' novel under the same title.
Apparently, Alan Rickman will be the voice of Marvin the Android, and Warwick Davis will be the operator of Marvin the Android's robotic suit. Rickman has not been officially confirmed yet though, although his casting was posted on the site run by Douglas Adams' official biographer.
For more / the complete article where I found this information, here.
-Chelle of Slytherin.