Here is the open source iphone app list in alphabetical order:
1.ABC 123 –
Sequence memorization game.Utilizes Cocos2D.(itunes link) (source code)
2.Artifice –
Strategy game where you try to get to the other side by moving boxes out of the way.Utilizes Cocos2D.(itunes link) (source code)
*3.Battle For Wesnoth –
Fantasy themed turn based tactical RPG game available on several platforms and now the iPhone/iPad. (itunes link) (source code)
4.Colloquy –
Conversion of the most popular Mac IRC client to the iPhone.(itunes link) (source code)
5. Countitout-
A generic counting app.(itunes link) (source code)
6. Diceshaker-
Dice rolling simulator designed for role-playing game enthusiasts.(itunes link) (source code)
7. Doom Classic-
Classic 3D first person shooter. (itunes link) (source code) (build instructions)
8. Ecological Footprint-
Calculate, display, and record your ecological footprint. (itunes link) (source code)
9. Fosdem-
Calendar app for the Fosdem open source conference. (itunes link) (source code)
10. Freshbooks –
Open Source iPhone app that enables usage of Freshbooks web invoicing software from your iPhone.(itunes link) (source code)
11. Gorillas –
Classic Worms/iShoot turn based shooter type game converted to iPhone from basic. Utilizes Cocos2D. (itunes link) (source code). 1249ouFh83XA
12. Go Go Lotto –
Open source iPhone app for lotto ticket generation. (itunes link) (source code)
13. iStrobe -
Turns the iPhone 4 flash into a highly configurable strobe light. (itunes link) (source code)
14. Last.fm –
Software that enables usage of the Last.fm platform for personal radio stations. (itunes link) (source code)
15. Mobilesynth-
A monophonic synthesizer designed for live performance. (itunes link) (source code)
16. Molecules –
Allows you to view 3D models of molecules and manipulate them through touch.(itunes link) (source code)
17. Mover –
Allows you to transfer stuff from one iPhone to another by “flicking” it to the other device.(itunes link) (source code)
18. Natsulion-
A basic twitter client converted from mac.(itunes link) (source code)
19. NevoChess –
A Xiangqi game. (itunes link) (source code)
20. NowPlaying –
Allows you to check local theater listings, and check rotten tomato ratings.(itunes link) (source code)
21. Packlog –
Backpack journal client.(itunes link) (source code)
22. PlainNote -
Simple Open Source Notepad.(itunes link) (source code)
23. PocketFlix –
Find movies, and manage your Netflix information.(itunes link) (source code)
24. Puff Puff –
Beautiful underwater 2D game utilizing Cocos2D and Openfeint featuring unique physics based gameplay.(itunes link) (source code)
25. reMail –
E-mail client featuring ultra-fast search. Removed from app store, but source made available. (source code)
26. RobotFindsKitten –
Port of a very silly “classic” ASCII game.(itunes link) (source code)
27. Sci-15 HPCalc –
Calculator app based on classic scientific HP-Calculator.(itunes link) (source code)
28. SpaceBubble –
Space game featuring core graphics, and accelerometer usage.(itunes link) (source code)
29. Star3Map –
Augmented reality star and planet charting application.(itunes link) (source code)
30. Task Coach –
Personal to-do list and task manager.(itunes link) (source code)
31. Tubestatus –
London train schedule tracker.(itunes link) (source code)
32. Tux Rider –
iPhone port of the extremely popular, and beautiful 3D Tux Racer game.(itunes link) (source code)
33. Tweejump –
Platform jumping game inspired by Icy Tower. Utilizes Cocos2D. (itunes link) (source code)
34. Tweetee –
Enhanced version of the Natsulion Twitter Client. (itunes link) (source code)
35. Tweetero –
Basic twitter client with image uploading.(itunes link) (source code)
36. Twitterfon –
Super-fast intuitive twitter client.(itunes link) (source code)
37. ViralFire –
Unique game where you are a dodging blood cell.(itunes link) (source code)
38. Wikihow –
A reader app for the popular how to wiki site. (itunes link) (source code)
39. Wolfenstein 3D Classic Platinum –
If you haven’t heard of Wolfenstein post below so we can say a prayer for you. (itunes link) (source code)
40. WordPress –
Client for managing WordPress blogs.Also has an iPad version. (itunes link) (source code)
41. Xpilot –
Simple massively multiplayer arcade shooter from the early days of the internet. (itunes link) (source code)
42. YourRights –
Pocket database containing a summary of your legal rights. (itunes link) (source code)
43. ZBar –
A barcode reader open source iphone app. (itunes link) (source code)
Check them out if you are working on something similar or think they might have a feature you could use there’s no reason to re-invent the wheel. Always make sure you understand the licenses as many of these open source iPhone apps are GPL and require that you open source your app.