Use Keyword Rich URL’s to Your Advantage:

Often people view the URL as one of the most important parts of an ad. The ad
title sticks out the most, but many people factor in the URL more than the copy. By
changing your URL to a keyword rich URL you can sometimes raise your click
through rate by 50 – 200%. A new throw away domain name only costs $8 at
GoDaddy.

If you have some high selling affiliates you may want to reward them by giving
them their own keyword rich domain. This can also help some of your affiliates get
their message through to customers since a few bad affiliates can get messages with
your URL in it blocked from being received by people using AOL or similar email
clients.