Okay, you all know that
@username + message
directs a tweet at another person, and causes your tweet to be saved in their “replies” tab.
But did you know that “D” in front of a username automatically makes it a direct, or private Tweet, only viewable in that person’s “direct messages” tab?
Or how about these?
WHOIS and then a person’s username will retrieve profile information for that user on Twitter.
GET and then a person’s username will retrieve the latest Tweet from that person.
There are others shortcuts too - just search Twitter support on Google.