One of the worst things I see people (and pardon me, usually ladies, but guys do it to) is to have an "organizer" that has nice places for your checkbook, cash, credit cards, drivers licence and so on. Usually (per the article) in there somewhere is the social security card or at least the number. Lose this, and all in one easy package is everything necessary for someone to take over your identity, drain you checking account and max out your credit cards.

Guys do the same thing, except instead of the check book, they carry a blank check in their wallet. Routing numbers and account numbers for the checking account are on the check.

My advice, try to carry at least some of these things separately.