1. Protecting yourself from the sun. All it took was one skin cancer lecture my first year of med school, and I haven't laid out in the sun since. I cover myself with sunscreen religiously, and encourage anyone I'm with to do the same. And it drives me crazy to see people at the beach laying out in the sun, almost naked and bright red. One in three people will get skin cancer in their lifetime, and having fair skin increases your chances.
2. Motor vehicle safety, i.e. placing your infant in a rear-facing child seat until at least 12 months of age and 20 pounds, and a forward-facing child seat until at least 6 years of age and 60 pounds. Furthermore, don't place your child under 12 years of age in the front seat (air bags kill kids!), and use a child seat with a 5-point harness (not a booster seat with an adult seat belt) until your child is at least 40 pounds.
3. Proofread what you write. Spelling and grammatical errors drive me crazy. (However, I do know that I am not completely exempt from making them occasionally. I am, after all, not completely perfect... ;)
4. Don't waste food. For whatever reason, I can't seem to throw away food until it is obviously too old to eat.
5. Letting your cell phone ring and interrupt church/lectures/conversations/etc.
6. Lateness. I can't stand being late, but I don't mind it as much in others.
7. Eating in front of people without offering the other person some (I mean, that's just plain rude).