Tumblr - A feature rich and free blog hosting platform offering professional and fully customizable templates, bookmarklets, photos, mobile apps, and social network integration.
Alcamy - Free, open self-learning platform. Learn & teach anything.
Soup.io - Soup is a tumblelog, a super-easy blog that can do more than just text: post links, quotes, videos...
EduDo - EduDo is a video discussion platform
Postly - Turn your photos into REAL beautiful postcards. Available on iPhone, iPad and Android. Make friends and family smile with a postcard!
Golden - Mapping all human knowledge