Gifsicle is a command-line tool for creating, editing, and getting information about GIF images and animations.

contains gifview a great slideshow tool for multi-frame gifs.

Animator5D - Very simple-to-use framework for rendering 5-dimensional animations (x, y, z, time, some color value) as an animated gif. This requires ImageMagick to combine the frames, but you can still render them without having it installed and just combine them with some online gif maker.