Some ideas I have for future side projects:

Parallel Asteroids
An Asteroids-clone where all of the different parts are parallel threads and/or tasks. This way I can exploit parallelization in Haskell further and test out all the different parallelization techniques.

C= 64 Basic Interpreter
Use Parsec to write an interpreter for the C=64 BASIC language. This was the first programming language I ever came in contact with and bringing it back to life would be interesting.

Parallel functional steering
Design and implement different parallelization strategies for existing steering algorithms, e.g. as implemented in OpenSteer. Is the performance using a nearly pure approach much lower?

Gettings things done in Haskell
Implement a console-based application with a streamlined and process-oriented interface to manage tasks, contexts, priorities etc.