I want to write a quick post about a fantastic free resource that I have been making great use of in my recent research. If you have Scottish ancestors then it could be worth your while to visit the National Library of Scotland's website. They have a range of Post Office directories free to view on the site in PDF format. They cover areas throughout Scotland, and range from 1773 to 1911.
Some areas are better served than others, with the big metropolitan areas like Glasgow having more records to view than small areas such as Peterhead. I managed to find listings for my ancestors in both the Glasgow and the Ayrshire directories. In total there are 694 directories to choose from.
The Post Office directories are a great resource for discovering where your ancestors lived at a particular point in time. Some of them also list occupations, adding another useful piece of information to your research. Some also include advertisements and business listings, and as such can give an extremely interesting glimpse of the business practises of the past.
Take a look at the Scottish Post Office Directories here.