Here are some XNA Websites:
creators.XNA.com The official community site for Microsoft's XNA. Samples, forums and great links to content
XNADevelopement.com Quite a few tutorials plus sample code and links.
XNA101 This is the list of the Tutorials from XNA101. Some great stuff in here.
GameProjects.com This site has downloadable community games for free. Most include source code so you can get an idea of what others are doing.
Ziggyware.com This site has some excellent community submitted articles about XNA. Check them all out. It is also updated frequently about news for XNA as well as other community aspects.
These are useful articles on various programming aspects
Generics Collections: "BCL Generics" "List", "Dictionary" What is this stuff? This article goes through all the current Generic Collections located in the Base Class Library. While somewhat technical and sometimes assuming you have prior knowledge of the old collections methods, this article goes through each one indepth making it invaluable for learning the Generics Collections.
Rotation, Vectors: "Sin & Cos: The Programmer's Pals!" This article goes indepth about vectors, moving on an axis and much more dealing with our favorite Trig functions: Sine and Cosine. A must read!
C# Scripting with Lua This article really opened my eyes to alternative methods of programming. Even if you don't want to use Lua (it's a scripting language) by the end of it you'll begin to see other methods for adding in content to your games. Once you've gotten the basics of C# down give this one a read.
NeoAxis Engine - An excellent engine for C# which includes a non-commercial version for creating freeware (read the EULA for all rules regarding use)
GameDev.net - A site with information about game programming for multiple languages. It has an active community as well as reviews, articles and more.
GameAI.com - A site for Game AI.
AIGameDev.com - Another site for Game AI