Handlescout is a free service that notifies you by email when your desired Twitter username becomes available.
AcctWatch monitors accounts for you. It checks diligently for each account name that you're looking for to open and immediately emails you when it does. Who knows when your dream handle will open?
Unless you have a registered trademark, there's not much you can do to get any site to hand back a handle. Let robots check for you! 🤙 🤖