I've put up two videos on imagemagick today and yesterday covering some of the basics from making canvases and composites and basic effects. You can check the first out here and the second here. Imagemagick is one of the most useful programs out there, and can be a huge boon for automated imageprocessing and also making little modifications (like resizing and minor adjustment).
I'll be doing more like this just because of imagemagick being such a huge and useful world. Specific ideas are welcome.