Now this is a concept that I can see going places on the PlayBook and BlackBerry 10. Jason Ernst has released a very minimalist HTTP Web Server app for the PlayBook that lets you serve HTML pages or files from your PlayBook. For now it serves out the files in your Share/Documents folder on port 8080 and does not allow you to change the port or put any security on the page.
For now this may be useful for quickly sharing a file with a friend on the local network or doing some quick HTML design. Once you fire up the app the documents can be access from another pc by going to http://your.playbooks.ip.address:8080.