Holland had it on 2 ships last I checked though it's risky to use. You are required to pay book price for a single travelor, then if they find you a match you will be rebooked at current prices.
When I looked: 35 day trip 3400 double price, 6000 single, 8000 through match program. If you do it early I guess you could pay deposit and cancel if they dont find a match.
Best bet is to find a roommate through this site or others. You can book through any travel agent and they will split the cost and send documents to both parties.
11 cruises in 2012, 90 nights at sea visiting 15 countries
8 cruises in 2013, 56 nights at sea visiting 7 countries
Next cruise: None scheduled
PM me if you need a cruisemate for any Europe, transatlantic, or Panama Canal cruises
Date, ship, cost pp