The Complete Photo Guide to Crochet by Margaret Huber is basically a crochet stitch encyclopedia, although it does contain a few interesting patterns that use some of the stitches.
There were a few techniques that were new to me (or I did them so long ago that I had forgotten) including one called intermeshing crochet. It looks complicated, but is simply two mesh designs worked over each other. (Mesh is double crochet, chain, double crochet, chain...).
Another cool pattern was a spiral shape worked in four colors.
If you like to work with yarn, this is a book you won't want to miss.