Gridmount is a MacFUSE file system handler for Valve’s GCF and VPK files enabling you to mount them as drives inside Finder.
Backpack Viewer 2 lets you easily view Steam Inventories when on the go. Supports multiple games.
TF2 Backpack Viewer lets you check the backpacks of you and your friends for the “#1 War-Themed Hat Simulator” wherever you are! It also caches previously loaded backpacks so you can view them offline.