For my fourth year project, I somehow managed to convince four other people that they wanted to help me create a 2D/3D physics engine.
Leveraging everything I had learnt from my third year project, it was surprisingly successful. It has already been used in two games, with possibly more to come.
Video of the 2D sandbox:
Subversion repository: http://svn.draknek.org/torquetome/trunk/physics/
My third year project was the development of a 2D physics application - you can see videos on Youtube here and here.
Unfortunately, due to some bad design decisions it wasn't usable as a library for a game, but the lessons I learnt from it were invaluable. It was a fun project and an excellent prototype for what became Large Polygon Collider.
You can download my source code from my Subversion repository at: http://svn.draknek.org/physics/code/.
Physics and Collision Detection - talk for Warwick Game Design (20/06/2008)