How do I register my service dog in Virginia?

Under the ADA, service dogs are not required to be registered. Though it's not legally required, several companies offer it.

(* FOLLOWING EDIT BY MEMBER RW 1/7/2015 *

Legitimate, legal service dogs are not required to be registered through any organization. They do not have to be certified or have an ID. The only licence required is the one issued through your state that all dogs within its boundaries are required to have.

Although several internet sites offer registration, certification, ID's, licenses or vests to make your dog a service dog, none are legal. That'd be like buying a doctorate degree online without going to any school and believing its real. Of course it isn't. REAL Service dogs go through about 2 years of training to become service dogs. Anything you buy from a company online is legally worthless. It's for novelty purposes only. It won't hold up in court if your caught fraudulently portraying your pet as a service dog.