This evening I played around with freelensing—holding a camera lens in front of the camera without mounting it, so that you can tilt and move the lens around freely. Like a tilt-shift lens, this allows the plane of focus to be other than a vertical plane in front of the camera. Unlike a tilt-shift lens, it’s very hard to control precisely.
SLR lenses and mirrorless cameras make a good combination for freelensing, because the SLR lenses are designed to be farther from the sensor than the mirrorless camera’s mount. Therefore you have a bit of a gap to move and tilt the lens around. I used a Canon FD 24mm f/2.8 lens and the Olympus E-PL5. I cut the sleeve off an old black T-shirt to put over the barrel of the lens and the front of the camera, blocking stray light from getting in between them.
Mounting the camera on a tripod is a big help, to give yourself a free hand, and so that only one part of the equation (the lens) is moving. Other than that, it’s mostly a matter of trying to make something look good on the LCD, and taking a bunch of shots.