SiteCycler in < 90 Seconds
(w/ no affiliation to the sites featured therein)
SiteCycler is a digital signage web application for realtime website display. Think of it like an online Powerpoint where all the slides are live embeds of other websites. It's perfect for kiosk displays and superfluous lobby monitors, anywhere you've got a screen and a collection of sites you need to cycle through.
SiteCycler is free, requires no signup or credentials to use, and takes just a couple minutes to get started using.
SiteCycler runs best in Chrome but does just fine in Firefox, Chrome, and Opera. No active support for Internet Explorer, but you're more than welcome to try it.
Source on GitHub. GPL licensed.