GIF Animations [multiple picture frames in one file] can be used for creating image slideshows, screencasts, text banners or even stop motion animation movies. Some MySpace and MyBlogLog users also use animated GIF avatars to attract eyeballs.To create an animated GIF online, all you need is a set of images (in any format like jpg, png, etc) and Glickr.com, a free site that will convert them into an animated GIF movie of predefined sizes that you can use as profile avatars or post them on blogs.
Individual images can be as large as 1 MB and you may directly grab your Flickr pictures inside Glickr.com. You may also change the speed of your animations [like how frequently the image transitions happen]
Some people find animated images as annoying as blinking webpages but they are a good medium for sharing photo slideshows in situations where Flash is not an option.