Who needs a Nintendo DS Lite, what with the fancy graphics and touchscreen. That's more sass than I need in my portable gaming. Give me some crappy graphics, some clunky controls, and a healthy splash of nostalgia, thank you very much.
Something like this portable Atari will do the trick just fine. It's everything you need to play your favorite first-gen video games on the go, even cleverly using the big honkin' cartridges as a sun shield, protecting the screen from glare if you ever decided to venture outside (not likely, I know). These aren't mass produced or anything, so if you really want one you're going to have to bribe creator Ben Heck until he agrees to make you one.