I also carry a small revolver (with permit) but i take it with me to most anyplace that is secluded or new to me. i wish i didnt feel it is necessary but it is more of a sense of security rather than anything else. Im more concerned about other people than the wildlife. Anyone seen the movie's Deliverance or Wrong turn? there's a good reason. haha. I think overdoing it is slightly rediculas, like the guys that work in the gun store, they have a elephant killer on there hip with 3 extra clips, a gun under each arm, then a "back up" on there ankle just incase, oh ya, dont forget the quick open "special ops" knife taped to there forearm. one small gun "just incase" is one thing but preparing your self for a one man war is another, those guys need to put down the guns and go make some friends, they scare me the most.
watch, wallet, car keys, cell phone are also included in this category.
as for geocaching adventures specifically:
GPSr
my dog (part of the reason i do it, exercise for both of us)
water bottle
bug spray
lightweight cloth gloves (for sorting through brush)
pen
notepad
disposable camera
trade items
cache website printouts
hat (helps with ticks)
2 small maglights
gerber multipurpose tool
all this neatly tucked in a small bag. (well not the dog)
oh ya, and my girlfriend.
glow sticks would also make for fun swag plus could have a use in a pinch.