These pages contain some attempts at mapping the Imperium, which is part of the Traveller campaign setting. There are plenty of other attempts out there, though none, as far as I can tell, add to the detail of data available.
Currently, the following services are available.
The map pages that make up the map, and the information it contains, are built on top of a web services layer which can be accessed via a REST interface. Currently, this is just read-only. The interface is quite simple, and best described with the following examples.
http://dev.glendale.org.uk/traveller/system/5.html
This gets information on system number 5, returned in HTML format.
To get the data as XML, request a .xml or .txt file instead (both
return XML, the difference being the content type it defines).
http://dev.glendale.org.uk/traveller/sector/1.html
Get information on sector number 1.
http://dev.glendale.org.uk/traveller/sector/The Reft.html
Get information on The Reft sector.
Data returned as XML may be rendered by a stylesheet, depending on your browser, so fetch the Text version instead if you really want to see the raw XML.