Speaking of nifty pillow things, Ostrichpillow's “Mini” travel pillow boosts the comfort level of your little nap breaks, which I find are key to keeping my energy and alertness up throughout the day. You can slip it onto your arm or wrist for laying your head down on a desk (as seen above), or wear it on either hand to catch a few upright zzz's on the train/bus.

It's small enough to keep in a bag or backpack without being too obtrusive, so it's easy to power nap just about anywhere (accounting for, y'know, social mores and all that).

Get it for $40 on Amazon in your choice of two interior colors.