some people don't use a GPS for the hobby, but it's a lot easier with one. Also caches can take on all kinds of forms, for instance...I've seen fake bolts in posts, a fake outdoor pipe, it looked like you could attach a hose to it, but instead you unscrewed part to get to the log. Fake rocks, fake acorns, etc.... my most evil hide was a magnet attached to an electrical box with the log on the back. The front of the magnet was just random letters, it didn't look out of place at all. A few other cachers had to return 3 times to find it.
Ones like that would be a real pain to find without a GPS, but some like ammo cans or decon containers can be easy enough to find once you get within a 100 ft or so.
By the way TC, if you get into it, you'll find you'll go through that 23 in your zip code in the blink of an eye. I'm starting to have to go 20 miles or more just to find caches. It's been a very rewarding hobby for me. My username there is the same as here,
This hobby is great for finding new areas you never knew existed, you'll find areas in your own town you never knew about before.
Here's a link to my profile in case you wanted to read some of my logs, a few mention metal detecting:
http://www.geocaching.com/profile/?guid=6b02fee7-63a0-4c55-9cf9-91e9ce156af7
It's not the hobby for everyone, some people make an account and find a few caches then never log on again, but if you really get into it you'll find it very rewarding.