Since you are rebranding, you might be better off finding a name where the .com is available just to avoid the hassle of being shaken down if you get big later. Companies that just ponied up the money when they got big are dropbox (formerly getdropbox.com) and facebook (formerly thefacebook.com). It seems like recently you don't even need the .com (e.g. famo.us and socket.io), so you could go that route if your name is short and easy to remember.
Since you are rebranding, you might be better off finding a name where the .com is available just to avoid the hassle of being shaken down if you get big later. Companies that just ponied up the money when they got big are dropbox (formerly getdropbox.com) and facebook (formerly thefacebook.com). It seems like recently you don't even need the .com (e.g. famo.us and socket.io), so you could go that route if your name is short and easy to remember.