clipped from: econsultancy.com   

Non-search commands

Try entering the following commands into the Twitter ‘post’ field, rather than as a search query. Results will appear in a dropdown overlay at the top of your Twitter feed...

GET username

This simply grabs the last tweets from a user, for example if you 'tweet' 'GET lakey' you'll be presented with my last tweet (and you won't actually tweet anything).

WHOIS username

A quick way of checking out a user is to use the WHOIS command. Tweet 'WHOIS lakey' and you'll see the following, in a dropdown (and once again, you won't tweet anything yourself):

"Chris Lake, since Sep 2008. bio: Editor in Chief at Econsultancy, blogger and entrepreneur. location: London, UK web: http://econsultancy.com"

FAV username

This adds the last tweet by that user to your favourites.