I just got 08 Murrays and wear a size 13, I don't have too much extra room in these. I have heard good things about the XXL Factions with guys that were 14 plus. They are a great binding and the hinge will make them easier to get on and off. There have been some threads on this topic in the past, I don't know what you would search for though.
I sold a pair of Ronix divide bindings to Tim Duncan of the San Antonio Spurs last year and he had a size 15 foot as well. He got in them with no lube no problem. Ronix bindings are great for people with big feet. The divide are on the low end of the binding spectrum but I think that they make the same size in the oxford which is their high end open toe boot this year. A buddy of mine rides them and love them. If you have 15 feet odds are good that you won't be able to go with a closed toe boot. Good luck.
im thinking the new Hyperlite focus boots should also be able to fit some huge feet in them because of the true floating tounge. Try those out for sure.
I wear a 13 and i like my binding roomy. Ive had CT 3ds and CT ONE's and there is def room in there for a 14 maybe 15. Otherwise I would pry go with some old Parks bindings in a XXL. In my opinion one of the best designs ever. Lots of room, loosen and tighten. If anything breaks you can usually fix it yourself and they go mondo cheap on ebay. Oh yeah my 3ds ct were xxl and ones are 13-14.
I have also ridden the Magnum Transits and the XXL Alpha's. The Transits are a much better boot than the Alpha's. I wear a 13 and the Magnum's fit me well, but I think I would have been better off with an XL instead.