I witnessed a fascinating presentation, this morning, on a project which has digitised the first map of London at building level, and overlays it with data from other sources:
http://www.romanticlondon.org/
The data sets are freely available, but the British Library claims copyright over the map images - I'm sure some of you will have your own views about this.
I shall notify the project's creator, Dr Matthew Sangster, about this post. He would be a good speaker for a future GLAM conference.