Texture Modification using Render Targets, with some Stencil Buffer Action
http://www.madgamedev.com/post/2010/08/17/Article-Texture-Modification-using-Render-Targets-with-some-Stencil-Buffer-Action.aspx

StencilCratersTutorial3440283811.zip

XNA4StencilMirror3843542491.zip

SkySphere Sample
http://msdn.microsoft.com/en-us/library/bb464016.aspx

XNA4SkyBox8630432049.zip

XNA4SimpleSound

XNA4SimpleSound.zip

XNA4Sound – using SoundNodeHandler

XNA4Sound.zip

XNA4SoundXACT

XNA4SoundXACT.zip

Creating and Playing Sounds
http://msdn.microsoft.com/en-us/library/bb195038(v=xnagamestudio.40).aspx

Playing a Sound (using SoundEffect)
http://msdn.microsoft.com/en-us/library/bb195053(v=xnagamestudio.40).aspx

Looping a Sound
http://msdn.microsoft.com/en-us/library/dd940203(v=xnagamestudio.40).aspx

Adjusting Pitch and Volume of a Sound
http://msdn.microsoft.com/en-us/library/dd940201(v=xnagamestudio.40).aspx

Playing a Song (using MediaPlayer)
http://msdn.microsoft.com/en-us/library/dd231914(v=xnagamestudio.40).aspx

Using XACT
http://msdn.microsoft.com/en-us/library/ff827590(v=xnagamestudio.40).aspx