There are 2 sticky threads at the top of this forum that could provide you with some information regarding checking if a name is trademarked or how to trademark it if that's what you want to do.
If it's a name I thought would take off I'd:
-do a trademark search first to avoid the disappointment of doing all the website, promotion and stuff only to find out you can't use the name.
-once the trademark is pretty well on it's way, register a business in that name. Again, depending where you live, you could be disappointed that the name is taken.
-seeing domains are relatively cheap, having purchased it now before confirming the above I don't think would be a big loss in the whole scheme of things right now.