I was in the mood for a good RPG for the DS.  
 
Any suggestion for one with an interesting plot?

So far Final Fantasy the 4 Heroes of Light is pretty interesting for me. There's also Dragon Quest IX and Sonic Chronicles. 
 
But if you wanna see crazy anime titties flopping everywhere then check out Super Robot Taisen OG Saga. Even though they're somewhat covered up, I'm surprised it got a T rating.

DQIX is not a story driven game by any means but is excellent if you just want some old school JRPG fun with a fully customizable party - can't comment on 4 Heroes.
 
SMT: Devil Summoner had, imo, a fairly engaging and a-typical RPG story - set in Modern day Tokyo you find yourself trapped when Martial Law is declared in response to a Demon Outbreak - you've got to find a way out of the city in 5 days or find a way to stop the disaster. Tactics style gameplay.

" So far Final Fantasy the 4 Heroes of Light is pretty interesting for me. There's also Dragon Quest IX and Sonic Chronicles. 
 
But if you wanna see crazy anime titties flopping everywhere then check out Super Robot Taisen OG Saga. Even though they're somewhat covered up, I'm surprised it got a T rating. "

I'm always on the looking for good RPG's myself on any console(except 360). I'm an old school RPG gamer and I have been playing Chrono Trigger on DS and pokemon platinum. I also picked up Dragon Quest IX but haven't touched it yet.

If Pokemon is considered an RPG... Then that. It has a very deep psychological story.

The world ends with you is my favourite ds rpg by far. It's very action oriented and has a genius battle system. 
 
Shin Megami Tensei: Devil Survivor is another great one, strategy rpgs aren't for everyone, but this is a particularly good one. 
 
Then there is always Chrono Trigger and Dragon Quest IX for more old school rpgs.