I was flipping through this guy's album (which is pretty damn good IMO). He must've visited an air show of some sort and took some really nice hi-res shots of a B17 and B24.
http://www.starfleet.com/liem/photos/other/misc/tn/b-17-sharp-usm-1024.jpg.htmlIf you search around in there (there's a ton of pictures) he also has some of the B17 on the ground from different angles.
They'd make excellent wallpapers.
[edit: doh, use
this link to get a thumbnail page]