Essential C by Nick Parlante
The basic features of C. From Stanford CS library.

Introduction to Programming using Java by David J. Eck

Pointer and Memory by Nick Parlante
An introduction to pointers. From Stanford CS Library.

Guide to Network Programming by Brian 'Beej' Hall
The best socket programming tutorial in Internet.

Win32 API Tutorial by Brook Miles ( theForger )
Learn Windows Programming quick and clear.