Unsicht-Bar is Berlin's completely dark restaurant. Diners order from a cryptic menu, and then are escorted into a pitch-black dining room (the servers are sight-impaired). I had a blast.
www.unsicht-bar.com/unsicht-bar-berlin-v2/en/html/home_1_idea.html
www.travelmusings.net
Updates
Unsicht-bar can cost you an arm and a leg: about 50 euros for a main course. I notice that this restaurant's website also keeps you in the dark about its prices.
Is this your business?