Intro to C:
http://www.cprogramming.com/tutorial/c/lesson1.html

C references:
http://www.cplusplus.com/reference/clibrary/
http://www.acm.uiuc.edu/webmonkeys/book/c_guide/

The GNU C Library:
http://www.gnu.org/software/libc/manual/html_node/index.html

Why C?:
http://www.cprogramming.com/whyc.html

Network Programming:
http://beej.us/guide/bgnet/

The C Language:
http://www.di-mgt.com.au/cprog.html

Simple DirectMedia Layer:
http://www.libsdl.org/index.php

GNU Compiler:
http://www.mingw.org/

10 Commandments:
http://www.di-mgt.com.au/src/tencommandments.html

Cython 'Python to C':
http://cython.org/


Short C Tutorials 'Pointers':
http://www.loirak.com/prog/ctutor.php#pointers

Data Structures:
http://en.wikipedia.org/wiki/List_of_data_structures