For one of my classes¹ I will have to buy a domain name. Of course, the instructor mentioned that the hard part of the assignment will be choosing a name. I remember seeing a website that allowed you to enter a desired name and showed if it was still available, and on which extensions (.com, .net, .org, etc.). I even put in "camomiletea", and noted that it was taken on .com, but not .net. I don't remember where it is, and I didn't realize that it would be useful for me in future, so I didn't bookmark it. Does anyone know what I'm talking about? (I won't choose "camomiletea.net" though.)

¹ Management of Information Technology

i think most companies that do registration provide that service. One of the most cheapest and popular that i know is http://www.godaddy.com

Haha, I was just about to recommend their show-what-is-taken feature, because I'm faaaaaar too familiar with that website.

I think you're thinking of Network Solutions' WHOIS service.