can you simply make the n770 show a web page from your server, with a meta refresh, and then have a simple CGI on the web server to generate a random page?

as to turning the display on and off by time of day, would a simple cron job be sufficient?

ideally, use a movement detector (passive infrared thing with a relay attachment to an adapted USB mouse's button?) so that it goes into deep sleep mode until someone is near.