Traveller is a science fiction roleplaying game that dates back to the 1970s and was originally designed by Marc Miller. It is still in production by Steve Jackson Games (who do a very nice version based on GURPS) and soon to be released by Mongoose Publishing.
The original goal of Worldgen was to provide a map of the Traveller universe for an RPG campaign that was starting. This map focuses on the Imperium, but there are plans to extend it to surrounding sectors. The map data is based on a mixture of sources found on the internet, which probably vary in how official they are.
Some of the data used can be found at SJ Games. See notes on Data Import and UWP for details on how this data was interpreted.