Home of Milkshape 3D, a useful tool for editing and converting 3D meshes of many kinds.
If you are currently a student this site gives you the ability to download complete versions of a lot of Microsoft's development software for your use on projects.
Information, help and downloads for Microsoft's DirectX graphics SDK.
Open source 3D rendering engine. Although not as fully featured as a professional game engine, is highly flexible and has been used on some impressive game projects.