[R] Different type of legend?

[rkevinburton at charter.net]

How would I create a legend that looks like the attached image? 
Basically all of the color boxes are right next to each other and the 
text is below. This kind of arrangement allows for many more items in 
the legend. Using the legend() method seems to top out at about 14 items 
(that will fit in the horizontal plot).

Suggestions?

Thank you.

Kevin