Random dungeon generators, MML parsers which produce better-than-Famicom chip music, fancy font libraries, polygonal terrain generators, and just about everything else imaginable. And this is with what's essentially a primitive, "early access" version of the product.

The best part is that unlike something akin to "Dreams", or making weird stuff with redstone in "Minecraft", Fuze is totally code-based-- which means the things made in it are maintainable, extensible, and easily shareable.