This may be old news for many of you but for those not familiar: - Bill W2CQ

Using Pathfinder Online to Discover QSL Info

Pathfinder Online lets you type a callsign once and search more than 75 different sites for QSL information with a few mouse clicks. Simply type a callsign into the Target Callsign box and then click on one of the search buttons; the results of this search will be displayed in the frame below the horizontal divider. If the search fails to yield a QSL route, click on another search button.

http://www.dxlabsuite.com/pathfinder/WebClient/