Joinos is a browser WebOS. But not yet another, its fast enought, user friendly and has a number of usefull apps, its Social Web OS, with desctop + gadgets. It's little like MacOS but in a browser. It has a file system where you can store(any), view (photo, video, audio, text, docs, presentations ...) and edit (text, docs...) files. You can communicate with your friends and groups (join or create) with chat, group chat, audio/video calls, exchange files, make live channels (like Justin.tv but p2p in Joinos), message wall, mail app (live notifications, add attachments from joinos fs) - everything in real time and in one browser tab without reloading page.