While playing OpenTTD on playbook, I find I often want to zoom and pan. I think the multi-touch capabilities of the playbook can be exploited to enable this. A two-finger pinch/stretch in the touch area could be interpreted as mouse wheel scrolling. This would make it easier to zoom to a specific point on the map and make the game easier to play. I think this would be true of other SDL-based games that use the mouse wheel.
A more generalizable version of this idea is making available several multi-touch gestures (pinch, two-finger swipe, etc.) and allowing them to be mapped to different actions through the sdl-controls.xml file. Then something like a two-finger "pan" motion could be mapped to right-click drag in OpenTTD to pan the map. I think a good first step would be just supporting the mouse wheel and worry about the rest later.
I'm interested in diving into the source and solving this myself, and I will fork and make the change for myself anyway, but I wanted to get input from others and make sure I'm not duplicating work.