Yes, I'm apparently now an Apple whore. But come on, theres some cool stuff for this thing!
Depending on your device you'll be able to take photos or not, so I'll separate the photo apps from the drawing apps.
Drawing
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Adobe Ideas: The one that prompted me to post this thread. A really nice drawing app, its vector based so you can zoom in as far as you want to add details without it getting all blocky and weird. Really smooth. If you only get one app, get this one. Its free, but has an in-app purchase for $5 to unlock layers if you want them. Oh, and it seems to get your images out of the program you have to either screenshot them or email them to yourself with the in-app emailer thingy.
Sketchbook MobileX: AutoDesk drawing app, bitmap based and its also really nice. MobileX is the free version with only 3 layers and limited brushes. Full version ($3) has more.
Buddha Board: Go for minimalism, and your drawing slowly fades away. You can always take a screenshot with your device if you want to save something you've done.
Photography
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Gorillacam: Guess it was made as a promo for those Gorilla tripod things. This is basically a replacement for the built in photo program, and even looks the same but has more features like displaying a grid, self-timer, time-lapse, burst mode, etc. Free.
Instagram: Seems to have some social networking photography thing...but you can snap pics with it, apply one of a bunch of different retro-looking filters, and then post the image to Facebook, Twitter, or whatever this built in network thing is. I think some of the filters look cool, and its free so what the hell, right?
Since I just got a device that has a camera I dont have many photo programs. And Im a cheapass that goes for free stuff whenever possible. I'll post more if I find something neat. Theres a free mobile Photoshop available that allows you to do some tweaks to your images. Have to try that out.
I'll have to draw some stuff or take photos and post them in this thread.
EDIT
Woah, they have AutoStitch! I can make panoramas on the go! Well, if I bought it I could.