I just bought a DSi and got Scribblenauts. Anyone got additional recommendations for games?

Depends what you're into. I've got Elite Beat Agents (rhythm game), Soul Bubbles (casual game that makes good use of the stlyus/mic), Monster Lab (Pokemon-esque, lots of minigames), Big Bang Mini (kind of like Gradius, shooter), and some others, which are all enjoyable. Final Fantasy Tactics A2 is good if you like that kind of thing

For download content, I picked up Dr. Mario and Brain Age Sudoku (didn't plan on getting the whole game, so this chunk was a good deal).

Take it back and get a DS Lite, save yourself some cash.

DS Lite, new: $129.99

DSi, used: $130.00

I'll keep it. Plus, doesn't the Lite only support WEP?

Yes, just like the DSi. Don't let the box fool you, WPA only works in DSi-supporting games/software. All other DS games are WEP only.

Also, shorter battery life (up to 5 hours less), and no GBA slot. Even at the same price I'd take the DS Lite.

Just sayin'.

That aside, Mario Kart and New Super Marios Bros.

I'd say The World Ends With You, but since Play still haven't shipped the copy I ordered I can't really comment on it.

"Ace Attorney" games. There's three Phoenix Wright ones and Apollo Justice. There is also "Miles Edgeworth: Ace Investigator". A flash demo came out last night and I was playing it.

Same stuff as the previous games, but there's additional mechanics... you control your character on the screen and walk around, stopping and pressing "Examine" to find clues.

Plus a "Logic" system where you can keep track of the various clues you find and link them together logically to come to a new conclusion, although if you choose the wrong clues you lose health. Or logic, or whatever it's called.

As the first example where the game teaches you the mechanic, there's been a murder in your office, and your office is locked when you're not in it. Thus, by linking these two facts together, your character realizes the location of the murder was not by chance.

How has there not been a metroid game on the DS. (If you mention hunters I will stab you).

If you like platformers, you should definitely get Yoshi's Island DS. Really great game.

Zelda: Phantom Hourglass is really fun as well, although it's a bit easy.

Don't bother with New Super Mario Brothers... waste of money.

This guy knows what he's saying.

I have a decent collection of DS games... Of them, I suggest:

Sonic Rush - This is what sonic needs to be. 2d. FAST.
Metroid Prime: Hunters - About as good as the first Prime IMO.
Zelda: Phantom Hourglass - Classic Zeldy action.
The World Is Not Enough - Very original game, I loved it. Try playing on BOTH screens, with two sets of controls, and two characters, but only one brain :p

I could not recommend Ninja Gaiden Dragon Sword enough. It is a beutiful game with a beutifully simplistic control scheme. When I purchased it from Amazon it was dirt cheap.

The control scheme is a little weird and it feels "empty" and "small" at times but it's a FPS on the DS what do you want from it... anyways it was fun once I got into it.

Can I mention metroid pinball? >_>
I really enjoyed that :p

I also liked

Marvel Trading Card game (but I'm a nut for card games)
FF Tactics A2 (though that got old towards the end, never bothered finishing it)
Puzzle Quest (think bejewelled, but matching gems gets you mana to cast spells)
Luminous Arc (rpg similar to FF tactics but I found it more fun)
Elite Beat Agents (normally I hate rhythm games, but this is crazy)
Castlevania (the first DS one, not a big fan of the later ones)

And a friend of mine is in love with some weird game called "Rune Factory 2 A Fantasy Harvest Moon"
Which plays like Harvest Moon, except that the cows and stuff are monstery, and you have to beat them up to get them working for you, everything you do levels up (chopping wood, bashing rocks, fighting) and eventually, you pick a wife, have a kid and then start playing as the child I couldn't get past the repetitiveness of harvest moon type games, but if you're into that you'll probably love this.

Not sure what games your into, but my personal recommendations:

Final Fantasy IV (a 3d remake of FF 2 on the SNES)
The World Ends With You is a very.. different game. i like it, it's fun and challenging, especially when controlling both the top and bottom characters, but it's got a good amount of substance. Although if you stop playing for too long, you'll most likely feel like you HAVE to start over.
Either of the Professor Layton games (they're logic-puzzle games)
Any of the Super Mario RPG games

I own all of those (except the layton games, but I have played the first, and I know the second is pretty much more of the same), and they're excellent IMO.

Haven't played Kingdom Hearts 358/2, although i own it. But I hear good things, so if you are into the KH series, it's definitely worth looking into.

I loved new super mario brothers and I enjoyed zelda for a while until my kids lost the cartridge

What's this? No Contra 4?
No Trauma center?

SHAME UPON YOU ALL.

What about the FF: Crystal Chronicles game? My friend and I want to try playing through that one.

Contra 4 is ok, but I wouldn't put it in my top ten or anything.
Trauma Center is just gimmicky and meh.
So try and shame me all you want, I'm immune =p

Contra 4 was great, until my rage set in.

I need to finish Zelda: Phantom Hourglass. I played a bit today and got the rest of the treasure maps, now just need to get the rest of the ship parts and beat the last boss.