Picaboo - Picaboo is a web-based image publishing and printing service that allows you to create personalized photo books, cards, and scrapbooks.
Metastream - Watch streaming media with friends
Juicebox - Spectacular HTML5 Image Galleries Made Easy
Watch2Gether - Watch2Gether is an app that allows multiple people to watch the same content simultaneously and interact with each other while watching.
novaGallery.org - Beautiful php image gallery - easy to use, with modern responsive design, private mode, themes, languages
StreamParty - StreamParty is a watch communiry, that allows you to watch video streams in sync with the people you care about, on multiple services.