The Wide World of Railroads is a series I began in early 2012 where I use a 1 to 3 (1:3) crop-ratio to create "faux"-pano style shots of railroad scenes.
This shot of the CSX in Folkston was one of the first times that I shared a photo in the ratio. I like the way that the crop brings the train into the shot as the main actor. In this case it seems to work so much better than the original image.
As I'm shooting railroad scenes, I use the grid in the viewfinder of my Canon DSLR to try and imagine how the shot will look when cropped. It requires me to think differently.. because of needing to allow space at the top or bottom (or both) for cropping later on.
Another ratio which is gaining popularity is the 16:9 ratio which is the same that is used on a HDTV. With so many images being seen on HDTV's these days, it is a natural also.
What is your favorite ratio? Have you tried some shots in untraditional ratios?