http://www.ajaxwhois.com/

Ajaxwhois is much better than this: the same principle, but it looks up a lot more TLDs, not only .com and .net, but a bunch of other ccTLDs, like .hu too ;)

I mentioned this on my site a while ago. The problem is the Instant Domain Search uses a database of registered domains, and until recently it hadn't even been updated in a long time.

I built Instant Domain Search in October because I was having a hard time finding a name for another project of mine. Others started linking to the search tool, so in mid-November I set up a script to keep the name list updated nightly.