Google Code Search
If you’re ever looking around for a piece of code to do something, then you should try Google’s Code Search.
For example, say I’m looking for some C code to parse RFC 2822 mail headers (which, strangely enough, I am). I go to codesearch and put in a search term of lang:c rfc2822
That gives me back a bunch of results, but say I want to look for something with a BSD license to use with Vacation, then I just extend that search with a license:bsd term, which gives me the great news that SMail (which I used to run 13-14 years ago now) has a librfc2822 directory, which deserves further investigation!
