My top choices are Knights in the Nightmare or GTA: Chinatown, the former being likely hard to find, and the latter being likely hard to get my parents to actually let me own. :\
Besides that, Big Bang Mini looks pretty fun, and Chrono Trigger DS has been in my mind for a bit, though considering Sean said he'd let me borrow it, and considering I know most of the bonus content now, there are definitely better choices.
Anyone have any opinions on these?