Raspberry Digital Signage displays web pages from LAN, Internet or internal (SD-card-hosted) folder in a restricted full-screen view. See the home page for cheap and extremely powerful web-based digital signage solution with the Raspberry Pi.
Raspberry Slideshow is focused on quick-to-set-up image and video slideshows for the Raspberry Pi. It plays all media contained in a USB key, fetched from a network share, from a Web/FTP server, from a folder of your Dropbox account and loaded via scp as well. See the home page for media slideshow digital signage.