The front-end is in scala now, but I find students with a java background can generally pick it up in a couple of weeks.
Projects on the scala side:
* improving the dynamic graph layout --- I've run this project a couple of times before, but its the kind of thing that's never really "done", so its good for undergrad projects
* visualising/editing non-commutative generators --- Supports work of David and I to implement non-commutativity in the core. Also there are some interesting open UI questions to solve here.