Gravity Gun: This is a nice little package I found on the net which is similar to the gravity gun in Half Life.
2d Landscape Creator: This little beauty is quite remarkable. Its unfortunate that the developer did not continue with it past ver 1.0. If you want to create a 2d landscape with physics and texture painting, then you need this!!
Terrain Tools: The fastest way to create a fantastic terrain.
As I find more create packages, I will be adding them here, so come back and visit again soon as you may find something very usefull!