if you are thinking about making your domain name for example a trademark, you can check to see if the trademark has been taken.

to do this, you need to search the United States Patent and Trademark Office database.

go to this link to check:

http://tess2.uspto.gov/bin/gate.exe?f=searchss&state=pppsah.1.1

their database will tell you who own the trademark of if its available.