Nice chart, Paul!
I began companion planting at the same time I began gardening organically back in the mid 1960's and still remember much of what is listed here. For those who have not tried this technique, I encourage experimentation.
Some plants, especially herbs and garlic, will attract or repel certain insects not only on themselves but also on other plants. Knowing which ones do what can help cut down on insect damage and, thus, the amount of insecticide one feels compelled to use.
Perhaps the most famous companion planting is the Three Sisters--squash, corn, and pole beans.
Traditionally grown together by Native Americans, they really do grow better together than they do separately.
Here's the story: http://www.birdclan.org/threesisters.htm