Rub is a synonym for Massage. This domain can be good for Online Massage Parlor Directories, Online Massage Bookings, Private Masseurs, Masseurs at home services, Professional Masseurs.
1. New extension (top)
2. CENTER is little difficult to brand due to center & centre (you need to own CENTRE too)
3. Rub center (does not sound popular term) ,. net is also available (as @Nerevar mentioned)