Disgaea DS - Fun story, good gameplay, insane level cap (9999), and perfect for a handheld. It's easy to spend over a hundred hours playing this game and working your way up to fight the completely insane Uber bosses. I find Disgaea games are such a perfect fit for handhelds because when I'm doing a bunch of grinding* I like to be able to move around as well.
*I say grinding, but it's actually pretty fun, it's not like the completely mindless grinds of a lot of JRPGs, the item world allows for constant challenge so there is still strategy to consider.
The World Ends With You (DS) - Interesting story about people being forced to play the Reaper's Game with their lives at stake. Well written with some decent characters and plot twists. Unique action RPG gameplay making good use of the stylus. Get's a bit tricky controlling two different characters with two different control schemes, but fun regardless. Also, unique for a JRPG, not insanely padded, no random encounters and the game is just as long as it needs to be. If you haven't played this one, you should.
Mario and Luigi: Superstar Saga(GBA). A decent JRPG, gives you a bit more interactivity in the battle system than most. It's kind of silly at times, but it has it's moments. Not really as good as the Paper Mario series, but pretty decent.
Mother 3 (GBA) - Sequel to Earthbound. Has a quirky world and one of the best stories I've ever seen in a video game. Even extremely minor characters have a good amount of development and it's easy to get attached to the main characters. Pretty much a must play for anybody who likes JRPGs.
