Scotlandspeople ($$): Scotlandspeople is one stop shopping for anyone doing their Scottish family history. This is the only place you will get original records for census, civil registration and Old Parish Registers. They have a large database for wills and other records.
National Library of Scotland: The National Library of Scotland is a free resource for those researching their Scottish ancestors. They have a wonderful digital collection from city directories to maps and everything in between.
Scottish Archive Network: This is a group of Archives in Scotland who have put their collections online in one place to search. If you find something of interest you can contact the archives and see if you can obtain a copy of the document.
The Statistical Accounts of Scotland: This is a searchable database where you can search for the town where your ancestor lived and find out more about the town. This will help put flesh on the bones of your family story.
ScotlandsPlaces ($$ & Free): ScotlandsPlaces is a subscription website but some items are free to search. You have tax rolls for everything from farm horses to watches. You can search for the area where your ancestors lived and find out more from maps and images.
The Scotsman Archive ($$): The Scotsman Archive has access to the Scotsman newspaper from 1817 to 1950. The search is free and the cost to view the documents is reasonable.
Scottish Genealogy Society: They have been promoting genealogy in Scotland and assisting researchers since 1953.
Glasgow & West of Scotland Family History Society: This is a very active society and they have created many resources to help the researcher with ancestors in this area.
The Scottish Association of Family History Societies: Not sure if there is a family history society in the area where your ancestors lived? Then check out the Scottish Association of Family History Societies to see if one exists.