It's a great sales tool, especially for complex applications that normally require large install files, database setup, complex configuration etc. and are therefore difficult to share with a prospective customer (think IBM or Oracle products).
To show our widget I took out 2 minutes to create a basic demo. Feel free to request a machine on this test site so you get an idea of exactly what we do: http://dl.dropbox.com/u/16347737/yComb.html
(I have only set up an Alfresco ECM demo with the sample above, but essentially any windows/linux app would work here).
My question: Would this be useful for the startup you work for -- why or why not?