WhoIs sites for gTLDs
One of the fastest Whois sites on the Internet is fasterWhoIs. fasterWhoIs gives you just the search form; no fancy graphics or banners, nothing to slow down your page's download. Once you submit the inquiry, it's quick search engine searches the Shared Registry and provides a search report nearly instantaneously (depending, of course, on Internet network traffic conditions). For further convenience, if the domain is still available, the you can either register that domain immediately with one of the fasterWhoIs affiliate sites linked on the results page or through another registration service of your choice.
gTLD WhoIs sites include:
Many people don't realize that it is the responsibility of the registrant to make sure that the domain s/he is registering is not someone else's trademark! If you don't want to get into some hot water later on down the road, it's best to search your domain name to make sure that it has not been registered as a trademark by another person or company. The US Patents and Trademarks Office has posted a site where you may search registered and pending trademarks via its search engine, TESS. It only takes a moment and it's worth doing to avoid possible trouble in the future.