You want to quickly give a try to some XSLT or XQuery code? You can do
this with the online "sandboxes" linked below. They provide two text
areas: one for the input document, another one for your code, and display
the result of the transformation below the text areas. On the server-side
Saxon is used to run the XSLT or XQuery code.
The result of the transformation is displayed as you type, some kind of
your browser and that only Firefox and IE are supported at this point.
Blog (XML, Web apps, Open Source): http://www.orbeon.com/blog/