Although this two-volume collection of books has been out for some time, it provides a good overview of The LEGO Group and history of the minifigure.
Typical of most DK publishing books, you have a good combination of visuals and information that can appeal to LEGO fans of any age.
The main "LEGO Book" was the better of the two volumes, in my opinion, giving a sweeping overview of all things Lego today. However, if its a visual dictionary of LEGO minifigures you are after, then "Standing Small" doesn't disappoint.
Covering the origins of the minifigure (the first "official" minifigure debuted in set 600 in 1978. It was a policeman.) and going all the way through LEGO Speed Racer and Indiana Jones, "Standing Small" gives a good overview of how these denizens of the LEGO universe have changed over the years.
At 96 pages it can't dive too deep into each collection and set. In fact I found the LEGO Star Wars Visual Dictionary (also from DK) was able to cover a lot more depth and breadth of the different 'figs from this series.
In the end, I would recommend picking this book up from your local library, half-price book store, or once it goes on sale. The $40 cover price is just a bit much given the informational pay-out, but a good read never the less.
(Picture from The Brothers Brick Blog)