Difficult to know what to suggest without knowing how much they are prepared to spend on you. Personally I'd like a nice big f/2.8 prime telephoto, but I know that isn't going to happen.
Assuming you are talking about photography kit, and that lenses and bodies are too expensive, what about things like rocket blower, annual subscription to your favourite photography magazine, tripod, bag for your kit, flash gun, flash meter, remote release, filters, editing software, extension tubes?