We call it q1tifier (pronounced 'quantifier') and it's main aim is to make sense of numbers. E.g. if you search for the number '5000' one of the result is '5000m = about the length of 89 NASA Space Shuttles' (see it here! http://duuble.com/q1tifier/view/3/=5000)
Numbers don't really mean anything by themselves, so through this such numbers could be more meaningful! This idea spawned from seeing infographics that often compare numbers we real life stuff, and we decided to make a database for people to supply such small pieces of info and facts.
The database is completely free and open, anyone can add any fact or bit of info. There is also a very basic api that returns results in JSON format.
Help contribute some info/facts to the database! Link: http://duuble.com/q1tifier/