We've shown you how to create a time lapse video with your DSLR camera, but if you're looking for something a bit quicker and simpler, DIY web site Instructables shows us how to make an animated GIF from a series of photos.
After taking some pictures of clouds outside his house, user V-Man737 wanted to make a simple, small file that would animate them together after the fact. He found that previously mentioned open source photo editor GIMP was the perfect tool to make an animated GIF.
All you need to do is drag each image as a layer. If you didn't use a tripod to stabilise your camera, you'll want to make sure each photo is at the same angle by rotating each one, watching the stationary landmarks and lining them up over each layer. When you're finished, you can just save it as a GIF and specify that you want the layers to be frames in an animation. It certainly isn't as polished as the aforementioned videos, but with a bit of forethought you can make a pretty cool loop with minimal work—perfect for little animated forum avatars and the like. Hit the link to read the full instructions.
Time-Lapse Photography Processing Using GIMP [Instructables]