Kipon OM tilt adapter for Micro 4/3. Purchased on eBay.
Pros: Relatively solid construction. OM bayonet connects to Olympus OM lenses with little play. Up to 8° of tilt in any direction. Lens can also be rotated if desired.
Cons: Black anodized aluminium rear bayonet, integral with adapter body.
No scale to measure tilt.
No way to make sure that zero tilt is set.
No way to control fine amounts of tilt (the mechanism is essentially a ball-and-socket joint).
The locking ring with two small levers is hard to operate.
In practical use, I find it easier to leave the locking ring in a half-locked position that allows the lens to be tilted with some manual effort, but prevents sagging and accidental changes in tilt.