Well you can use sites like www dnsstuff.com to execute a 'Wois" query for that domain. This will tell you the registration date and the date the domain expires.
You can also check http://www.archive.org/web/web.php to see if the domain was owned before the current owner (right now it may be a dropped domain picked up by someone new), you'll see the archived pages if it was. This isn't 100%, but does give some clues.