What libraries have you found yourself missing when programming in C?

Don't get me wrong, the CPAN is certainly one of my favorite things about Perl. I have just never had a job programming something substantial in any language that was already 90% complete. I would certainly never say that "90% of every" application in *any* language "has already been written, tested, and deployed". Some of them, sure. But not all of them.

-- dug