Modern Life: Etiquette for Tipping

What are the rules for tipping your server? Do they apply to bartenders? How about if the owner of the restaurant is your server? And what if you had to wait a really, really long time for your food -- should you express your dissatisfaction by reducing your server's tip?
From Jonathan Gold of LA Weekly, here are his (opinionated, but valuable) "10 Handy Rules for Tipping." I can't agree with all of these ideas -- for intance, I don't tip 20 percent when you order and pay at a counter and someone brings you the food when it's done -- but agree that 20 percent is the right amount these days.

1.Tip 20 percent. Every time. Pre-tax? Post-tax? In practice the difference is no more than a buck or two, unless you're Joe Pytka. In which case there's a $10,000 wine tab, so it works out. But the idea that a tip is optional, or variable, is a useful fiction, even when the soup goes tumbling into your lap. The owner gets to pretend her prices are lower, the busboy makes rent, and you get to feel like a philanthropist. A win-win for all.
2.Yes, I know your parents still talk about when the recommended percentage used to be 15 percent, and that the practice is considered barbaric in Japan. But it's not 1973, and you're probably not in Osaka at the moment. 20 percent.
3. Yes, this includes the cost of the wine.
4. And extends to tipping the delivery guy if you order in - he's supposed to get less because he drove six miles to your house in a decaying, gas-gulping SUV?
5. And also includes tipping the bartender, even - especially! - if you're in one of those places that charge $16 for a vodka/Red Bull. It is considered gentlemanly to round up this 20 percent to the nearest dollar.
6. You've heard the rumors about how it isn't necessary to tip if you're being served by the woman who owns the restaurant? That it's insulting to tip a sushi chef. Or that in some kinds of places the tips never make it back to the waiters? You guessed it: 20 percent. 7. In a restaurant where you stand in long lines to order, waiters do no more than shuffle food from kitchen to table, and you pay before you are served - surely this is a different situation? A sound point. But still: 20 percent.
8. You are in a restaurant to pick up a to-go order, yet there is a tip line on the credit card receipt? The dude putting the order through didn't refill your water glass, suggest the endive salad or tell you his name is Tim, but he did do something. In this case, 10 percent is probably sufficient.
9. The nice woman at the coffee place who remembers how you like the foam on your double macchiato? A buck in the jar. Which if you end up buying a scone or something will end up being about 20 percent.
10. The parking attendant: Depends on how much you love your car, really. It's best to round up the fee to the nearest dollar and add two.