Find other domains sharing the same IP address
When taking over a site it's always good to check for any domain names the client might have forgotten about. Although shared hosting (or managing multiple clients on a dedicated server as Agaric does) will show all the domains pointing to a single IP address, it's still a useful way to look through and see which may be related, and should follow the site to its new home.
A number of services will do this for you. A good free one is: