Jacobite Express steam train crossing the Glenfinnan Viaduct on a cloudy day with Loch Shiel in the background.
This is my best selling image, taken in 2006 on a 6MP DSLR, it still sells regularly as a 30"x20" print.
I think with the popularity of the place due to Harry Potter, it is difficult to get an image like this nowadays because there are always hundreds of people around.