Garmin Vista C with topo map and UTM coords., and a paper topo map (with UTM grid). Sometimes I bring a UTM grid tool for more precision (like "Where's that darn water spring anyway?"). I also bring a Brunton 26 (small sighting compass) primarily for its mirror, and an itsy-bitsy Montbell compass/zipper pull on my lanyard.
But it's not really navigation; I could probably navigate without any of the above, since I stay mostly on-trail. However, and as others have pointed out, I enjoy the geographic snapshots I take, to know exactly where--and when--I was at any point on the trail, and to record special waypoints for future reference. Further post-processing of the GPS data meets all my mental masturbahtion needs: average rate, time/distance between points A, B, C, D..., and even break times.
I'm a bit dismayed that the latest GPS units are simply heavier and larger (OK, larger screens are good), which have delayed any thoughts of upgrading.