Many of you will be aware of the digital resources available via the American Armies "Combined Arms Resource Library"
A new addition to their collection is the Order of battle, United States Army, World War II: European Theatre of Operations, Divisions. This free 600 odd page document contains a huge amount of data about American WW2 divisions including who commanded units, what Regiments and battalions were in each Division , and what units were attached to any Division unit at any particular time. It also shows what casualties were suffered, what medals were earned and how many POWs were taken. In short a mountain of information.
The only problem is that the document is a scan of a mimeographed original so the print quality isn't ideal but that is really only a minor issue.
http://cgsc.cdmhost.com/cdm/singleitem/collection/p4013coll8/id/4079
Hamsterking
Blimey that sounds pretty comprehensive! Could be very useful for future games though :).