Image Manipulation Tutorials
Patrick Welker is producing a wonderful series of tutorials over at RocketINK.
I particularly like how he walks through the installation of the various packages in detail, adding in troubleshooting tips along the way.
The goal of downloading all these binaries is to have a versatile collection that exactly mimics what ImageOptim and ImageAlpha do and bring it to the command-line for easier scripting and macro building.
ImageOptim and ImageAlpha are great (I use them every day), but they mostly just simplify the command line tools. The RocketINK tutorials are worth the time.