Similar to the European Union digital library that went live a few months back, UNESCO has now launched a similar project called the World Digital Library. This online library contains various significant documents including manuscripts, maps, photographs, books and other types of documents from around the world.
This site is really easy to use and very interactive. You can use the time line at the bottom to narrow a search for documents for a certain time period. you can also browse in a variety of ways by time period, continent, subject, and document type. This is a great resource for primary source documents as well as just plain cool and interesting. Check it out