Image effects aside, I wanted to add a little about unusual compositions. Breaking rules can often be difficult as it both puts us beyond our comfy zone and the results don't always live up to our expectations, which can also put us off of trying again. I find that most of my photos adhere well to the rule of thirds and golden mean (or spiral) and there's nothing really wrong with that, as such photos generally end up being pleasing to the eye. But as a fairly keen photographer, I'd like to start getting more of those, "wow, that's different!" pics versus, "yea that's nice" ones. The picture of the excavator below is starting to get there in my opinion. Rather than worrying about putting the subject where the rules dictate, I focused on the story I wanted to tell with the image. Here's a monster of a machine that has been tired out by the amount work it has been doing all by itself. Sure you're tough, but a little help is always nice.
The original photo was very different and what you're seeing here is a substantial crop. In fact, the machine was centered towards the lower part of the scene, there was plenty of sky present, a few buildings were in the distance off to the right, and a little more dirt filled the lower portion. But by squeezing the excavator to the bottom right-hand corner and tightening in on the shot, the dirt mover actually appeared to shrink and become less significant. Why? Well without the buildings, power lines, and other visual cues, it's now more difficult to relate sizes of objects; plus there's a bit of compression from the zoom lens which exaggerates the dimensions of the rocks in the foreground and the dirt hill to the left.
Anyway, the idea I've hopefully presented, especially if you'd like to improve your composition skills, is to sometimes try to fit the photo to the story you're trying to tell versus trying to fit the story to a set a rules.