Here is a cool robot capable of moving on the ground and over the walls. VertiGo, created in collaboration between Disney Research Zurich and ETH, has two tilting propellers (2 DoF) and one pair of steerable wheels (4 wheels total). Due to its capabilities, VertiGo can travel through challenging urban and indoor environments with agility.
With its two propellers, the robot can make a floor-to-wall transition easily, with thrust applied towards the wall and in an upward direction using the rear and front propellers. The above video shows this robot in action.