I have officially started my first open source project. It is a program called Par Explorer. What is Par Explorer? The purpose of it is to allow you to open a PAR or PAR2 file and view all the packets stored in it and the contents of each one. All it does is let you view the data. You can't change it or create it.
I wrote this program more as a testbed for learning how to read PAR/PAR2 files. I'm working on a separate application (not open sourced yet), that will do some more processing of PAR files. The purpose of this application is mostly to develop and test the code to read and process PAR files. It also gives me a chance to learn how to write document based Cocoa apps. PAR files make use of some interesting concepts such as MD5 hashes, CRC32 checksums and Reed-Solomon codes. I'd never done any work with these concepts, so this is something else I'm learning during the development of this program. You can freely view the source for the app over in the Subversion repository on the SourceForge project page, so if you are interested in any of these concepts, take a look. MD5, CRC32 and a large amount of PAR2 code is already there, if you need that. Have fun!