I'd want possibility to easiely create "virtual" physics, objects such as... pushables, barrels. In example, then you could create boulders blocking a path then player can push the boulder aside by moving it in the right direction(s) to clear the path.

This can be done with lua as well. Boulders - pictures, check from what side did player come and determine whether the "picture" will be attached to him or not...
but instead of writing so much code, yes, it would be useful to add another property to objects "pushable"