LBP's DLC is largely costumes and stickers, but there's a few decent kits and a music pack if you're into level creation at all.
Disgaea's DLC was largely characters, a few new chapters about Beryl, and some additional Item World modes for hardcore enthusiasts that came with online leaderboards and such for those who haven't sunk enough of their life into the game yet. The downside of most of the DLC is that you had to have cleared the game's story to access it, particularly the additional characters. Also, the pricing is a bit wonky - if you get the mass download pack, you're actually paying about half a dollar more than you would be getting all the things individually. I guess you're paying for the convenience, but the idea of bundles is typically to encourage you to get the whole mess for a lower price (LBP's costumes follow that rule), so NIS drops the ball a bit there.
On the other hand, most of the stuff in Cross Edge wound up being free, even if it is fairly small doses of content. I've heard mixed reactions to CE tho, so I've not gotten it.
No, I've been playing FFX. I am so hip and trendy.