Found on the second page of
http://www.onjava.com/pub/a/onjava/2005/10/19/challenging-java-dominance.html

"The best continuation-based frameworks are developed in dynamic
languages. By far, the most robust is Seaside. It's a framework based
on Squeak, a Smalltalk dialect. Seaside features fantastic debugging
support--you can actually inspect, debug, and change your code from a
browser."