nVidia's driver work pretty well for me.
Maybe a framebuffer driver so that my VT's are nice and fast, and switching to them is fast as well? (Would make me very happy)
Maybe a nicer, more friendly installer than integrates in a more friendly fashion with the distro package management?
Faster is always nice!
And i can bet the moment Wayland gets any traction in actual use rather than just conjecture then nvidia will put out a driver for it.