Tutorials
Cplusplus.com - A fantastic site with comprehensive C and C++ documentation, as well as tutorials
Tutorial on Pointers and Arrays in C
MS
theForger's Win32 Tutorial
Linux
YoLinux.com - A collection of tutorials for everything Linux (specifically linked is the C++ Development section)

APIs
MS
The Microsoft Developer Network (MSDN)
Linux
Codase.com
GTK.org
Apache C++ API

Code Repositories
Sourceforge.net - Code and project repository
Freshmeat.net - Code and project repository

Compilers/IDEs
GCC
Visual Studio 2005
Eclipse - This may take some configuration to be able to use to compile C/C++ code.
The Bloodshed Dev-C++ Compiler

I see that Dev-Cpp is listed here. I like Codeblocks because of all the compilers it is capable of using, while being very easy to pick and choose which compiler to use.

It also has the ability to use dev-cpp's devpaks, and use devpak.org to auto-fetch libraries for it's mingw distribution that comes with it.

The mingw that comes with codeblocks is more up-to-date as well. I point all my dev-cpp's compiler tools to codeblock's mingw distribution, as the older mingw in dev-cpp has problems with manipulating files, among other bugs.

Floating-Point Arithmetic
What Every Computer Scientist Should Know About Floating-Point Arithmetic

I would also suggest listing http://www.boost.org/ - there are days when I can't get anything done without boost