I've long been considering putting together a directory of projects whose code is fantastic for learning from. There's just too much code out there, and it would be nice to see lists of "great iPhone code to learn from", "effective and architecturally sound Ruby on Rails projects that scale", etc. This would really require some assistance from the community, but long term I think it would highlight code from quality hackers, and improve the status quo of programmers out there.

Any such thing already exist?