Most people never bother to take photos of clouds, because, well, they don't turn out very interesting. But, there's a quick little thing you can do to your cloud photos that will give them some oomph.
Here's a before:
I think this is lovely as it is, but to really turn it up; I do the following: + Boost the color a tad + Apply an edge burn
Here's what you get:
It's got more depth and becomes a little moody; dare I say?
If you're using a program like iPhoto; you can easily toggle with the color by clicking on 'edit.' iPhoto has an option in the 'effects' panel called 'edge blur' that works really nicely too. I suggest searching the internet for specifics on how to burn the edges a little or boost color in your specific photo manipulating program.
I use iPhoto and Photoshop for my stuff.