Go to Tweetgrid.
Select the size grid corresponding to the number of terms you want to track (the maximum is nine).
Enter the brand name (or any other term you want to monitor on Twitter) into the search window, hit search. You will note in the window above that I added REPLICA to a brand name.
And while we’re on the subject of Twitter, there is an article beng bandied about concerning ‘twitter-squatting’ wherein folk are using famous brand names as twitter usernames. The article contains a list of which of the 100 most valuable brand names are not yet registered as twitter names. So I am not linking to it for that reason.
Having said that, it wouldn’t kill you to go to Twitter.com and obtain your valuable brand names as twitter names. It’s free.