The article hyper-cliki : Web/Continuation describes how to write web applications with the continuation-based web framework UnCommon Web in Common Lisp. Very interesting, as Common Lisp itself is much more handicapped with continuations than Scheme - in Scheme continuations are first-class objects by standard, in Common Lisp they are not.
Continuation-based web servers have the advantage that the actual code can be structured very similarly to classical applications. You don't have to deal much with the event model of classical web programming and you rarely have to deal with explicit session constructs, because the session in a continuation-based web system is implicit.
There are continuation-based web frameworks for the following languages:
- [Smalltalk][1]
- [Common Lisp][2]
- [Scheme][3] (unfortunately no direct link to the web server itself)
- [SISC Scheme][4]
- [Ruby][5] [twice][6]
- [Python (via CherryPy and either Stackless or StateSaver)][7]
There are certainly more, but these are the ones I could find quickly.