Free

• http://c-faq.com/index.html

  Good straight to the point faq, covers specially confusing points

• http://www.open-std.org/jtc1/sc22/wg14/www/standards

  Official directory containing the latest free draft versions of the ANSI c specs

  The latest is: http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf

  The closest to the ANSI standard that you can get for free (it is a paid standard...)

  This should be quite close to the actual specifications

  Quite readable, and fun to find obscure features which you had never heard of before!

• http://locklessinc.com/articles/obscurec/

  Obscure stuff only. Cool.

Package managers

• https://github.com/iauns/cpm

• https://github.com/clibs/clib

• http://programmers.stackexchange.com/questions/170679/why-are-there-no-package-management-systems-for-c-and-c

• http://ccodearchive.net/