We offer domain add-on feature - it let's you host more than one domain on your current hosting account, all domain names will share your plan resources - disk space, email accounts, bandwidth, control panel. Please see the following tutorial on how to setup an add-on domain:
http://www.livingdot.com/tutorials/rvlightblue_addondomain.htm
If you are unsure that domain add-on is what you are looking for, please submit a support ticket.
