It seems kind of quaint to be recommending a compass in these days of GPS-everything. But it's nice to have an insurance policy when the batteries wink out and you're in the middle of Nowhere, USA.
The Brunton 8010G is small, light and rugged - perfect to slip into the daypack and forget. It has scales along the edges in miles and kilometers to make map reading easy and a small magnifying glass to help you read the fine print.
Its lime-green color helps it stand out in the dark confines of your backpack, and it comes with a lifetime guarantee. The only drawback? It doesn't float. But at $20, it's easily replaceable.
Buy it as a package with Compass and Map Navigator Book by Brunton ($28.95) and you'll be navigating like a pro.