Google has added related phrase results to the define: search command.

Now when entering a search phrases a list of related search phrases are displayed, this will help you to find relevant keyword information for you to target.

For Example enter, define:domain name, displays the following key phrases.

domain name system
domain name server
domain name service
fully qualified domain name
domain name registration
domain name registrar

__________________
Domainmonster.com Customer Support Team.
Domain Name Registration Information & Resources.

whilst not overly impressed when i tried it, i can see that it does have some uses i guess