Every photographer has taken a sunset photo. And why not? There are few opportunities to capture a naturally occurring scene with colors that are richer or more dramatic. The trick is to find something unique in a sunset to add a little extra interest.
On the technical side there are some things to consider. First off is making sure that no parts of the picture are over-exposed. Having a glowing ball of fire as part of a picture makes it easy to blow out highlights. A good place to get an exposure reading is slightly above the sun rather than right on the sun.
Another thing to watch out for is the white balance. A digital camera is, by default, going to set the white balance so that the sunset looks like normal daylight. This of course is not at all the effect you want. I get around worrying about this issue by shooting in RAW which allows me to set the white balance on my computer with no image degradation.
I particularly like the sunset picture below with the zig-zagging line of clouds seemingly rising out of the sun.