easyAPNS is an open source (free) system for sending Apple’s push notifications to a device. From their website:

What is Easy APNs?
If you are a native iPhone application developer, you may have heard of the Apple Push Notification service (APNs). There are a lot of excellent online guides on how to get your application to receive remote notifications… but what about the other piece of the puzzle… ACTUALLY SENDING A MESSAGE?!?!
This very cool project is brought you by Manifest Interactive.
*NOTE: I was NOT able to get this up and running on GoDaddy Hosting for some unknown reason, but the same exact files worked flawlessly on (mt) MediaTemple
Review Scraper is the ideal app to download App Store reviews on a global scale. The App can be downloaded HERE free from Google Code and needs to be compiled.
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Developers can easily track what people are saying about their apps and see how it ranks in all the App Store countries.
• Search for apps using a familiar interface.
• Translate app reviews into your native language (language support is limited to what the Google Translation API supports).
• Downloaded app reviews are saved and can be easily deleted.
svn checkout http://reviewscraper.googlecode.com/svn/trunk/
This was first talked about at 360iDev in San Franscisco early in March. These guys got it up and running quick. This is an excellent hub of information if you are a developer trying to find Open Source code to learn from or expand upon.
open.iphonedev.com
Here is another excellent tool for developers to track their daily/weekly/monthly sales figures from iTunes Connect. It’s the Open Source appsales-mobile app. It can be checked out of the GoogleCode Repository HERE using any SVN client. I use the free RapidSVN
From their site:
The newest reports can be downloaded with a single tap and all numbers are automatically converted to your (selectable) local currency.
With clear bar charts you’ll get a quick daily overview of how your apps are doing in the store. For each report you can view percentages of countries and each of your product’s share of the revenue.
The Graphs section offers trend charts for all or individual apps and a pie chart that shows revenue by region for a selectable date range.
I’m sure you remember the classic 1st person shooter Wolfenstein 3d. The creators iD Software have revived the game once again and ported it to run on the iPhone. Non developers can buy the game from the App store for $4.99 Interestingly though, if you are an iPhone Developer, the full source files for the game are released free under an open source license. A full paid ($99) iPhone developer license is required in order to compile the code on your own device.
The source code can be downloaded here from Id’s ftp server
If you are interested in running Wolf3d on the iPhone simulator you need to make some minor code modification. Instruction can be found at ghostradio.net