I've been asked why I copied tinyurl and the others with tw3 so I explained it briefly here. Basically, if you're using twitter, the difference between an eleven character domain name and a six character domain name is actually significant. To get more than 4 characters after the slash, I'll need over a million and a half entries in the database, which means, including all the paraphernalia, that URLs will be under 18 characters long for some time. Step 3 ... Profit!