Let's put together a Big Picture
It seems to me that there is so much open source stuff out there of different quality and importance to different people, that it's easy to only see the things you encounter from day to day. While there is Freshmeat's database, and GNU's software list, it is impossible to get the Big Picture of what is out there.
I can't believe this hasn't been done before, but if it hasn't I think we need to compile a list of what people define as important programs to them. If contributors stated a range of the most useful and/or important open source projects that they use or know of, a list could be compiled, perhaps at Freshmeat.
A short comment on why it is important (inc. what it does) could be made for each effort, and it could be catagorised, but in a more specific way to the appindex. It would probably be a great resource for both regular and potential users of open source software.