Looking at clouds moving in the sky is always magical to me. To think that all those forms and colors are just water and air. Sometimes I just sit on my balcony and look at the sky for an hour. I have also taken photographs of the sky, with surprisingly nice results: such cloud photos can be used for moody and mysterious backgrounds, like the one in the banner of this blog.
This video is not mine, but I wanted to link it because I like it. It is by someone more professional at skywatching: