Since their release of IronCAD Design Collaboration Suite 2014, IronCAD, LLC has been growing an extensive list of partnerships. The latest partnership is with TraceParts.
IronCAD, with its unique ability to create master-model structures or to build parts and assemblies within the same file, already has an extensive functionality to convert any component into a catalog part and reuse that geometry by dragging and dropping from IronCAD's Catalog Browser. If the user created "Attachment Points" to the geometry, those components snap into place allowing for very easy configuration of assemblies (and is one reason why I think IronCAD is a great tool for semi-custom machine design).
TraceParts is an online CAD library containing over 100 million 3D models, available free to IronCAD users through a Portal accessible from within IronCAD software.
These millions of files are all native IronCAD files, not neutral file formats. Although I can't confirm if Attachment Points have been added, it could be possible that they are and that would result in very fast and efficient means to add standard components to any custom design.
Sources:
http://www.ironcad.com/index.php/latest-news/22-news/226-dec-10-2013-traceparts-teams-up-with-ironcad
http://www.traceparts.com/news/press-releases/2013/PR05122013.asp