Wow, lots go good answers! Yes, in a way asking what the minimum is will be the same question. We may strive to take the least gear we can get away with, but then it really must still be enough to give you a decent chance to survive if things truly go pear shaped. But as you add just one more thing...and then another...at some point you have a pack you'll be tempted to leave at home given the excuse.

Thanks a lot for the comprehensive lists! Pictures would be cool, too. When listed it looks like a ton of stuff; it would be nice to have visuals to put things in perspective.