All-things-Mac weblog TUAW highlights a handy Terminal trick for adding OS X's double scroll arrows to both sides of your scroll bar. Just fire up Terminal (it's in the Utilities folder of your Applications folder) and paste (one line):

defaults write "Apple Global Domain" AppleScrollBarVariant DoubleBoth

You'll need to log out and back into your Mac before the changes take effect. If you prefer more traditional variants, you can actually tweak the other two options—place scroll arrows together on one side or separately at the top and bottom—in the Appearances section of your System Preferences. Since the point of keeping the scroll arrows next to each other is to minimize mouse movement, though, have the double arrows at both ends makes a lot of sense.