GIMP Plugin Registry

this script adds an "anitools" submenu to the "script-fu" menu with entries useful for creating (optimized) animated GIFs:
create scanlines: paint every other horizontal line in each layer with the current foreground layer. this can decrease the size of the resulting GIF and some people like the look :-)
set image framerate: set the frame rate for all layers in the current image.
set layer framerate: set the frame rate for just the current layer.  read more »

Save layers as GIF-Animation with more than 256 colors.

Screenshots and download: http://69b.org/cms/software/gimp#gifsicle