I 'll be 100% honest with you and say that you may have a dud here.
No doubt GetRegistered or even GoRegister would be heaps better.
But we are here to help each other so I engaged in some deep dredging and here goes it:
"get" means to acquire something so "register" must be a noun.
The commonest noun I could think is a cash register (may you can think of another).
Why not set it up as an affiliate cash register promotion? In fact, I stumbled upon one a few months back. Every retail business has one and they are now selling sophisticated ones, some are 100% PC based- do some research.
I would not spend more than a couple of hours on this.
Btw, if you were thinking of this name for a domain registry site, I woul say, sorry, but no. And yeah GetARegister.com would be the correct concept of my idea.