When I do real work, I usually architect and develop large scale Ruby on Rails applications in some form of agile environment. By chance, or so it seems, I have been responsible for inflicting several CMS style apps on the world, and I'm working on a new one...
I run my own consulting firm that specializes in solving hard problems, normally in the web app sphere. The general idea is that while most shops can give you a web app for the general case they are not used to think about scaling, constraints or complex domain problems, so that's where we come in.
So if you have something others have said is "hard", "difficult" or, preferably, "impossible" give us a shout. You'll find a link over to us above :)