The filter used in photoshop is called motion blur (duh!) and it is adjustable. You can push it to extremes to make it look like the subject is screaming, or tone it back for a more realistic effect, which is what I usually prefer.
But, often it's just the mood I'm in.

It's been very popular. Took some work to fine tune the technique so that it doesn't look fake. It really brings the boat out of the background.





And sometimes, just simply rotating the image can add some zing and make it more interesting.