Is there an .lxf file resource of production Lego sets?
The Eurobricks forum has a topic dedicated to user created LDD files of existing LEGO sets. 

There are currently four different versions of the #10179 Millennium Falcon made by different users:


yellost (23 August 2010) 
bbqqq (12 November 2010) 
Calabar (20 October 2012) 
kcoon (16 December 2013) 


There is also a topic for official LEGO sets re-created in ldraw.