In Japanese, santoku means "three benefits".
Not sure what it means when you apply it to this style of knife, but to me it seems like there are a lot more.
The Santoku knife plays the role of the chef's knife in Asian cuisine. Very thin and well balanced , the knife will chop through just about anything with ease and can create thinner slices than it's clunkier European-style cousins.
An added bonus is that most Santoku knife incorporate hollowed bevels on the blade to prevent thin slices of food from sticking to the blade.
Recently, the knife has been popularized by chefs/cooks on the Food Network, most notably, Rachael Ray.