Always loved the Severna Park's Fells Point layout in HO scale and thought it would make a wonderful bedroom railroad for a space challenged O scaler who loved scenery and a tight curve industrial layout.
Just think, a B&O C16 class docksider and a few favorite 40' cars would be stunning and a lot of fun.
Oh, and for those so interested the B&O Railroad Historical Society's The Sentinel had a great article in Volume 30 # 1 (First Quarter 2008) about the B&O in Baltimore. A lot of RR in a little space.