Same thing as the past ten years- finding and emulating the missing Nichibutsu "Moon" games. Of course, they have to turn up first, and I'd be glad to pitch cash towards these games.
Oh... and Owen Rubin's vector Tunnel Hunt (Tube Chase/Vertigo), as well as other lost prototypes (Malibu Grand Prix, Sebring), but that's not very likely...
"One of these days, I'm going to cut you into little pieces!"- Nick Mason, Pink Floyd