Digital images from Scotland’s Public Register of All Arms and Bearings in Scotland for the years 1672 (the year it was begun) through 1907 have been placed on-line at Scotland’s People, "The official government source of genealogical data for Scotland." Searching the images is free, though you do have to be an existing user or register as a new user to perform searches. Successful searches (and you can, for example, search for a full name or just a surname) will produce the following information: the full name; the date of the grant or matriculation; and the volume and page numbers from the Public Register. Unfortunately, viewing the images is not free, running £10.00 per entry (most entries are one or two pages. There is no additional charge for the second page of two-page entries). Still, if you are only looking for a few individuals, it’s a whole lot cheaper than flying to Edinburgh and going to HM New Register House to look through the volumes of the Register there.
I went ahead and did a search for one of the Scottish surnames in my family tree. The search for "Forbes" returned 45 entries. A screenshot showing the first eight appears below, so you can get an idea of the results you will see from a search. They also make it easy to print out each page of search results with a "Click here for printer-friendly version" link at the bottom of the page.
More information about the Public Register of All Arms and Bearings in Scotland, and coats of arms in general, as well as a couple of sample images from the Register, can be found on-line at http://www.scotlandspeople.gov.uk/content/help/index.aspx?r=554&1283.
The first heraldic authority to begin digitizing and placing on-line illustrations and basic information about the arms, badges, etc. that it has granted was the Canadian Heraldic Authority. This is still an on-going project for them, and new images are placed on-line periodically as the work of digitizing them is completed. The CHA’s Online Register currently includes pages 1 to 100 of Volume III and all of Volume IV (pages 1 to 538). You can access the Online Register, which contains the uploaded images and information from The Public Register of Arms, Flags and Badges of Canada, at http://www.gg.ca/heraldry/pub-reg/main.asp?lang=e&welcome=true.
I think it is great that the Court of the Lord Lyon and the Canadian Heraldic Authority are making their Public Registers so much more truly public by placing them on-line. What a boon this can be to heraldic researchers and genealogists alike.