Dummy content?

I thought I saw a plugin here but can't seem to find it now. Is there some way to edit the "dummy content" or "demo content" for the themes? I've googled and found some xml imports that I can stick in there so the themes can really show off all the style options, but I was wondering if there was a plugin out there that let you edit that content somehow so the WPMU users could "try before they buy" kind of a thing (like a demo).