I usually carry a GPS, a Garmin 60CSx. It has a memory card with both highway and topo maps for most of the US and Canada.

I use it for driving all the time and I always carry it hiking. I try not to rely on it, but I don't see any reason to tempt fate so I'm happy having it with me.

I also always carry a paper map and a good Suunto compass (and a keychain backup compass) when hiking, but if I ever seriously got lost, I'd be very glad to have the GPS with me.

Also, you may never purposefully hike at night, but you never know what might happen. I'm always prepared to spend the night outdoors, even when I'm just day hiking. A flashlight with batteries is an absolute must for me; in fact, I carry perhaps a few too many... <img src="/images/graemlins/smile.gif" alt="" />