Game controllers have some serious advantages for music:
they're simple, flexible, fun, and because they're shipped in volume,
often cheaper than DIY or even manufactured music products.

Our friend Chris O'Shea has an ongoing roundup of game controllers as instruments:

• Part I

• Part II

He wants more help: if you see some he missed, drop him a line! (between CDM readers and near near future,
we should be set!) Meanwhile, CDM is rounding up some ideas, too; I
just have to get through some paid writing now but expect something
next week.