Are there any "App Store quality" apps for creating animated GIFs from a series of image files?

You might install ImageMagick with brew install imagemagick and then use something like this:

convert -delay 4 *.png output.gif

-delay 4 sets the delay between frames to 0.04 s.

See http://www.imagemagick.org/Usage/anim_basics/ for more information.

I'd like to revive this question in the hopes of generating a more complete list of the available options which are either Mac apps or command-line tools (not websites).

These are the ones I am aware of.

• GIFQuickMaker [App, no longer free, very simple, but works and creates small images]

• Pixen [App, also no longer free]

• Gifsicle: Command-Line Animated GIFs [Terminal based, available via brew]

• ImageMagick: Convert, Edit, Or Compose Bitmap Images [specifically the convert program. Terminal based, available via brew]

(I've marked this answer as a community wiki in the hopes that others will add to it)