This domain actually has some value, though not so much as just the domain. I know exactly what I would do if this were mine. My suggestion to you is...
Design a site that lists and links to all the known estimator tools; estibot, leapfish, examinurl, and so forth. Be transparent and tell your traffic that its just for fun. You should easily be able to come up with a list of at least 20 or so. Go all out on SEO and hit up some social bookmarks. Your visitors will stick to the page like glue while they check each and compare the estimates from each tool. It would be a great site to bookmark and link to for these reasons. Get it ranked, and you should see some healthy traffic. Monetize. I would imagine that it would acquire a nice PR- use it to pass to some of your sites.
Just my two cents...
Reg to low xx resale
High xx for enduser.