If you are using Visual Studio 2010 - there is a GUID creation option.
Tools -> Create GUID -> Registry Format
and then trip off the surrounding { }
This is how i've always created my GUIDs for Page and Block types. If this is a new page type or block type, if you supply the GUID in code, when the site builds and the page or block type is added, EPi will use the GUID you provided for that type.
You can also use the Visual Studio integration. It creates the GUID for you when you're using the create new template command.
Throwing in another option...
You could also set up a macro in Visual Studio to generate the GUID for you. Check out http://www.mikebevers.be/blog/2010/01/guid-generator-macro-for-visual-studio/.
There is also some external websites where you can create GUIDs. My favorite is a site that can generate several at the same time. http://new-guid.com
I guess the easiest thing to do, if you're using resharper, is to type nguid and press Tab.
Hello,
What procedure are you using for GUID's when creating a new Content Type? When I see example of code that people have written there is often a GUID defined like this:
[ContentType(GUID = "abcdefg-1111-4f56-8a13-28ff2fc62960")]
public class SomePage : PageData
How is that GUID created? Are you entering the database and see what GUID that was generated for a particular class or how is the GUID chosen, in this case the "abcdefg-1111-4f56-8a13-28ff2fc62960"?