The way it shows the shorter / trimmed variants of what you type is interesting but not, I feel, particularly useful. It has a nice UI though and does seem very fast! It also only does com, net and org, whereas ajaxwhois, for example, does biz, us, info and ca.

Two alternatives:

http://www.ajaxwhois.com/ http://www.instantdomainsearch.com/

A "sort of" alternative (requires a click but comes up with better results for word mixes): http://www.bustaname.com/

I'd rather like to see one that can also do .co.uk, just being a Brit and all :) I have a few customers who would use such a thing.