Now that I have gotten back to Europe, I found Scotland's People to be excellent. it is run by the Scottish government. I had my great aunt's date of birth, parents names, and place of birth. With that information and the Scottish government website, I've managed to pinpoint ancestors right down to the farms on which they were born.
The site is free to search and look at the index information. You only pay if you want to open up an image and save it. They have old parish records & statutory records for births, deaths, marriages, etc. There are also census records, tax rolls, military records, wills, maps, photographs, etc. I actually verify stuff I find on Ancestry if it is Scottish with what the government website has (and have found transcription errors at Ancestry).