Yes we do! If you are a current Server Intellect client you can register new domain names whenever you need!
Please see https://www.serverintellect.com/hosting/domain/ for more information.
Log into your Account Administration Portal at https://unity.serverintellect.com/.
Then under My Services click on Domain name.
You can search for available domains and register the domains you need. The price per domain is $15 per year.