How to identify menus and commands in Visual Studio 2008

From Visual Studio 2005 SP1 on, there's an undocumented registry switch to enable debug messages which show the guid and id of a selected menu or command. To enable this hidden switch, you'll have to add a dword registry entry under [HKEY_CURRENT_USER\Software\Microsoft\VisualStudio\9.0\General] which is called EnableVSIPLogging. It should have a value of 0x00000001 (hexadecimal 1).

After restarting Visual Studio 2008, you can now identify menus and commands by pressing STRG+SHIFT and clicking on the menu or command.

For instructions on enabling this for Visual Studio 2005, see this article.

VSCT file format in Visual Studio 2008 SDK

Hilton Giesenow has made a fantastic How to video about the new vsct-file format which Microsoft is using in Visual Studio 2008 SDK. In contrast to other how to videos, just showing how to use the VsPackage wizard, Hilton shows every step manually. So you'll get a fare good understanding on each part.

You can find the video here.

Creating custom project types with Visual Studio

Mike Hadlow gives a fairly good overview on how to build a custom project type for Visual Studio:
Code rant: Building a Visual Studio Custom Project Type

Please note, that at least in Visual Studio 2008 you'll have to create a project template to show your own project type under File -> New Project. You don't get any error if you don't do this, but your project type will not be shown.