I have two geocaching bags - one for around town and a backpack for hiking.
Both bags have the following in common: gps, iPod (GSAK), camera, cell phone, Gerber multi tool (love it!), compass, lip balm, extra batteries, sunglasses, TB's, a few trade items, and pens.
The backpack contains a lot of trade items, matches, emergency blanket, water, snacks, dog treats, first aid kit, hat, water proof jacket, bug spray (even though I apply skin so soft before leaving), sunscreen, rubber gloves, toilet paper, cito and dog bags, and germex.
I love my 2 bags so much, and searched a long time for the perfect backpack, here is the link to the backpack:
http://www.ebags.com/mountainsmith/lily_re...?modelid=111478