Tumblr - A feature rich and free blog hosting platform offering professional and fully customizable templates, bookmarklets, photos, mobile apps, and social network integration.

Golden - Mapping all human knowledge

Soup.io - Soup is a tumblelog, a super-easy blog that can do more than just text: post links, quotes, videos...

Sutle - Save and organize resources into a directed learning path.

Postly - Turn your photos into REAL beautiful postcards. Available on iPhone, iPad and Android. Make friends and family smile with a postcard!

QuestBook - The fastest way to teach and learn