But for most of you who are used to instant result for everything (ajax enabled), then you have to try this : PCNames Domain Search. It does this virtually instantaneously domain search using Ajax, just like Google Suggest.
When you get unavailable in the result it will be shown WHOIS button for each domain to get more information of the site owner, or if a site is available for registration the search engine provides a list of companies that can be used to register it. I think this is where they get the money – not by direct reselling but from donations and commission from affiliates.
The most impressive thing about this search engine is its speed; it really is fast and will save a lot of time. There are also a variety of other tools available on the site as well, which are equally useful for web authors and searchers alike.
One of my favourite is Word Search which will show you which domains were available, deleted or expired according to any word you enter (try: Google).
Here’s the AJAX API from PCNames,