I want to display a website embedded in my own site and modify the DOM (e.g. change a button's color/size), similar to what Firebug is capable of.
I'm aware of the security issues that arise - my plan is to use this approach to do live website usability testing (A/B style).
I'm not limited to any specific RIA framework (yet would prefer Flex) - but it has to work without installing anything (so no AIR).
Cheers :-)