A bigger list is in the blog post: The Big List of Image Registration Software
published on the web as images (directly, as tiles or by image servers).
The tool will display a map (Zoomify format is supported in the beginning) from your server and allow you to specify a set of ground control points directly in the web brower.
Our georeferencing tool generates the georeference for your online maps. You don't need to upload your maps to us, they are displayed from your server.
From the georeference we will also extract geometadata for bibliography record in formats like MARC21 field 034 or DublinCore Box (new version, protype of the old version) as well as vizualization for cartometric accuracy analysis (protype) of the map.
Gregory I. - A Place in History. A Guide to Using GIS in Historical Research, http://hds.essex.ac.uk/g2gp/gis/index.asp
Fleet, Ch. - Putting old maps in their place? Practicalities of geo-referencing and delivering historical maps online. National Library of Scotland. The British Cartographic Society: Map Curators' Workshop: Mapping 2008: Making the most of maps: text of the article: Local copy.