Where check if a word / phrase is trademarked?

Hey here's a simple question,

where may I check if a word or a phrase is trademarked? There's a great web 2.0 word I would wanna register as a domain, but I could get in trouble if it's trademarked, so where could I check it up?

Thanks

//Twixx

This is the US government's site of checking if something is trademarked or patented. http://www.uspto.gov/trademarks/index.jsp Play around with your idea if it is trademarked, you might end up coming up with something better than you did before.