1) Konami's to bring parity and then some with the 48/60's: Time Pilot, TP84, Amidar, Scramble, Super Cobra, Circus Charlie, The End, Gyruss
2) MCR games: Tron, Satan's Hollow, Tapper first, then Kick(man) and the rest. (If JROK could build a replacement for MCR sets, I'd be the first in line for one!!)
3) Jungle King/Jungle Hunt/Pirate Pete.
4) All the Universal games: LadyBug, Space Panic, Cosmic *, etc..
5) Missing's, but simple ones from the 48/60's: Bomb Jack, Congo Bongo, Crush Roller/Make Trax, King and Balloon, Juno First, Pleiads, Xevious
Most importantly: Enable RLE or some other type of fast compression in the flash memory to allow you to get more games in at once.
Also: Improve the programmer software to show you % memory used as you are selecting games or show the size next to the game title and then let you sort by size to see what you can put in.
Finally: Enable an option to give vertical-style menu theme to the horizontal, or at least let you remove the "MULTI WILLIAMS" logo and the over-done bezel with all the williams art and give more room for the marquee and screenshot.