I typically always carry a topo, even on day hikes. I like to know the surrounding area. The names of the canyons, ridges, hills, etc.
I have one of those combo thermometer/compass things that hangs from your pack. I can't remember ever looking at it, other than looking at the thermometer.
So in a pinch (or the fog

I hope I'll find my way out as long as I've got the stuff.
I pick up my topo maps at Wide World of Maps, they have every map in stock, unlike REI that only has select maps.
All the discussion on the Topo software however has peaked my interest, I'll have to check that out.