Reselling Domain Names

[ejapan office]

You offer web hosting services. Or web design services. Or both. When
your clients need domain names for their websites, do you want to send
them to another site, possibly to a competitor, to register one?

Of course not. That's part of why domain name registration is a
popular service to offer. Reselling domain names provides an
additional service to attract and keep clients as well as another
source of recurring revenue. You can offer domain name registrations
on their own or bundled with other services you provide.

Please read more here
http://www.jpstream.net/articles//articles/1802/1/Reselling-Domain-Names/Page1.html