[acdha]

There are a couple of projects which try to make that really easy by allowing you to georeference a map by matching some common places:

http://www.oldmapsonline.org/ http://www.georeferencer.org/ http://maps.nypl.org/warper/

If you want a desktop app (handy with e.g. massive high-res scans) there's a fairly polished QGIS plugin: https://www.qgis.org/en/docs/user_manual/plugins/plugins_geo...

Once you've georeferenced something it's a fairly straight-forward process to either export as KMZ for Google Earth, etc. or export tiles which can be used with something like LeafletJS. I've used a master -> QGIS -> GeoTIFF -> gdal2tiles -> mbutil path with fairly low hassle.

I used this awhile back on http://www.wdl.org/en/item/2589/ and it was pretty interesting to see how the 1827 map was fairly accurate for the western part of the Russian empire but got significantly inaccurate as you headed to the northern or eastern frontiers.

[dalek2point3]

very interesting. I've been meaning to do a study where I track maps over time to get a visual picture of how the world was "discovered". Have you seen anyone else that has done something similar or any references?

[acdha]

I've certainly heard interest in that sort of thing but I don't follow it closely. It'd be a great project, particularly if it involved something like georeferencing TIFFs on the Wikimedia Commons.