Received notice today of some new (to me) search engines/sites. Can't verify that they are better than what we already know but here they are. I did a quick check of Toronto-Moscow flights (just for fun) and found plenty of options.

Departures from U.S. cities only and membership required. http://www.cfares.com/

Includes departures from Canada http://www.mobissimo.com/search_airfare.php http://www.dohop.com/

Lucy, Toronto