Some photos taken with an Arsat 80mm f/2.8 Pentacon Six lens on an Hartblei tilt adapter for my Nikon D90. The lens and adapter were purchased on eBay a few weeks ago; also got a Carl Zeiss Flektogon 50mm f/4, but haven't really tried it out yet.
Figured this was an economical way to begin experimenting with tilt photography. Can't justify spending a grand on a Nikon 85mm f/2.8 PC-E just yet.
All photos below captured with Nikon D90, hand-held, manual mode, RAW files post-processed in Lightroom, exported as JPEGs. f-stops are my best estimation at the time of capture.

Tilted down 8 degrees @ f/4

Tilted down 8 degrees @ f/5.6

Tilted down 8 degrees @ f/4

Tilted up 8 degrees @ f/4

Tilted left 8 degrees @ f/5.6

Tilted down 8 degrees @ f/4

Tilted down 8 degrees @ f/5.6

Tilted right 8 degrees @ f/4
Still a lot of experimenting to do, trying to understand the relationships and effects of the variables: tilt degrees, direction, focus plane, DOF, hand steadiness, etc.
I'll be posting some shots of the gear soon, so stay tuned...