Actually - TravellerMap.com supports PDF downloads using the API (doable from just the addressbar in a browser, although he mostly references from other web pages).
But, more importantly - none of the sites actually have the MgT data, IIRC! There are subtle changes in TLs, starports, etc.
However, TravellerMap.com still has you covered - go to http://www.travellermap.com/post.htm and you can enter (copy form the PDF and edit) the data you want. There is a PDF checkbox and you can also make routes, allegiances, etc, in the meta data, as well as generate output in several styles and with various options on what shows up (like names). It takes some playing around, but the results are good.
(The other sites, are great too - the first even has System Details if you 'drill down' far enough... though non-cannon, I believe)
EDIT: Oops -
navanod's post beat mine (didn't realize I failed to hit submit - similar first words and I failed to realize the preview wasn't mine till right as I hit submit!

)