The one I use the most is the Garmin Etrex Camo. It's really simple to use, fast, and compact. It has some hunter-friendly things in it like sunrise, sunset, and moon phases, and even calculates most productive times to hunt & fish. I've yet to validate that part, though. It does everything I need a GPS to do. If you throw it on the dash while driving, it'll even automatically turn the backlight on and warn you of upcoming turns. It runs forever on two AAs. It's cheap, too. You can get one for something like $129.
The only downside is that the Etrex series is relatively old technology, even though they're still on the market . I picked mine up 2-3 years ago. So it doesn't use WAAS, which limits its accuracy to 20-30 feet instead of less than ten. If you use a GPS for precise mapping of deer stands, etc, this might be a factor. But if you're using it to navigate, it'll definitely get you close enough that you'll spot what you're looking for before the unit says you're there.
Bought mine 3 yrs ago and only one friend at work has ever used it. I found that most areas I hunt, even the ones I never hunted before are pretty basic. You go up in the morning and down to come home. Or I follow a river or somthing that I know I wont get lost and I carry a compass just in case. For me it was a waste of money!
I would recommend a Garmin basic Etrex or the newer Garmin Geko 101 or 201. I am a huge GPS buff and love to play with them. Some of the new model will do alot of cool stuff with downloadable maps and built in compass and altimiter/barameter, But if your looking for a simple to use model to get you to your deer stand or back to your truck the Etrex or Geko. The Geko is not much bigger than some of the smaller cell phone out there. It runs on only two 'AAA' batteries.
Others have offered up a sighting of roughly 2 inches high at 100 yards as a good sighting scheme. In my own experience I have come to favor a sighting of 3.5 inches high at 100 yards. This allows for the individual to hold dead-on (directly in the middle of the top and bottom) the animal out to roughly 350 yards.
Magnum calibers such as the 7mm Remington and 300 Winchester will extend this slightly. At 400 yards I hold directly on the backbone of the animal. The drop at this range allows the...