The National Library of Scotland has a large selection of zoomable digitised maps.
http://maps.nls.uk/scotland/index.html
Information on places in Scotland arranged by county or you can search the whole database. Results include maps, photographs, Ordnance Survey name books and medical officer reports from the 19th Century. These reports give useful background information on living conditions and diseases prevalent in particular parts of Scotland.
http://www.scotlandsplaces.gov.uk
The National Library of Scotland has digitised over 20,000 maps at high resolution.
http://www.nls.uk/maps/index.html
This site has scanned images of old maps for England, Wales and Scotland arranged by county.
http://freepages.genealogy.rootsweb.ancestry.com/~genmaps
This site has lots of links to family history resources for Scotland organised into areas such as marriages, censuses, poorhouses etc. There are also some useful county maps showing parish boundaries.
http://www.scotlandsfamily.com/index.htm
The National Library of Scotland has made freely available historic maps of Scotland, England and Wales which are copyright free and can be used on websites etc.
http://geo.nls.uk/maps/api
View maps of places in England, Scotland and Wales mostly from the 19th and early 20th century.
http://www.old-maps.co.uk
