Well, there's always Lotus Viewcameras - http://www.lotusviewcamera.at/ - they make really nice cameras.

Robert Wite in the UK is probably the best place to buy new LF gear, http://www.robertwhite.co.uk/ . Used stuff I find on www.ebay.de, where the prices are a lot nicer (for the buyers) than in USA, and both prices and selection are better than UK (see how nice it is to be able to read several languages ).

Lots of links to producers and resources on www.f32.net

I have no plans to move to anything bigger than 13x18 myself, the only change I want is something lighter than a Technika 13x18. An Ebony 5x7, for instance...