My digital camera has a nifty feature which allows me to take photos at regular intervals. For example, I can take 100 pictures at 10 minute intervals. This allows me to effectively create time-lapse movies.
After loading the photos onto my computer, I use Adobe Photoshop Elements to batch-resize the photos into 400xM pixel GIFs. I then use a free tool, unFreez, to string the GIFs together into an animated GIF. Photoshop Elements also has a facility to create animated GIFs, but it's clunky and awkward.
See: SunStudy, CactusFlower