I claim personal responsibility for the sale of several Nintendo DS handhelds and games. I've really enjoyed mine, and was recently selling a co-worker on Super Scribblenauts (great game. buy it now).
My co-worker did in fact buy a shiny new DSi XL.
Of course, being a programmer at heart, and having created a few GBA homebrew games in the past, I got on the flashcart bandwagon with the DS as well. One of my favourites is Animanatee, a flipbook style animation application. I was a big Animator fan as a kid, so I had a blast with this thing as well.
Here is a sample of my wonderful art.