NIS America has just announced five new kinds of DLC for Disgaea 4: A Promise Unforgotten. Ranging from new characters to a special tournament, the new content will set you back 99 cents to $5.99 at the most per item.
Personally, I'd buy a "Pirate Survival Duel" just for the name alone. That sounds awesome.
Check out the full list of all the Disgaea 4 DLC here.