Honestly, you serious developers probably aren't the audience for this. It's more for the 18-month old crowd. But I built this app, and I'm extremely happy with it, so I figured I would share the love. And it's all thanks to cocos2d.
My son loves trains. After "mama" and "dada" his next word was "choochoo." We have some tracks a few blocks from the house and we go for a walk every night to go see the choochoo. But sometimes it doesn't show up and my son gets disappointed. So I figured I could make him something that might be a sort of stand-in.
Some midnight oil later, I got this app up on the store. Lots of user testing with the little guy, and it cracks him up. Adults seem to get some happy out of it too.
I can't emphasize enough how much cocos2d made it possible. I grew up coding in BASIC but put it down for art at some point. Had fooled around with xcode 2 years ago but was frustrated by how difficult simple game, animation and sprite stuff was. Cocos2d helped me rediscover my geek side.
Some screenshots:


This is about a train, the sun, the moon, some cows, some pigs, the stars... some parallax motion, some texture transforms and some particle effects- you know, all that. Oh and a sweet soundtrack.
Get your promocodes:
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On iTunes:
Thanks especially to the cocos community- Lam Hoang Pham for writing the CCTransformTexture class, Valentin Milea for TouchesTest demo, the Zwopple guy, and so forth. Good times.
Last note: I'm open to sharing my source, but not sure best platform to do it on. Any recommendations?