Interesting comments.
In all states it is illegal to pay less then minimum wage. However, there are 2 minimum wages (most people have no idea about it) one is the one that everyone gets, the other is a 'tipped employee' wage. (in some states the wages are equal) Ours is $2.83 an hour. It is true that if between the wages and tips a server doesn't make an amount equal to the 'normal' minimum wage the company has to make up the difference. However, many places will just tell you to claim more tips so that it equals that normal minimum wage. Even if you're already claiming 100% of your tips! Here is the min wages by state:
http://www.paywizard.org/main/Minimumwageandovertime/MinimumWageTIPRecevers
Most places do make the server tip the bartender even if they don't get a tip on a table. It's a % of sales...so if a table orders 10 drinks then doesn't tip...the server has to pay the bartender out of her pocket! The server also has to tip the busboy even if she gets stiffed for a tip, or if she clears the table herself!
Servers or bartenders prepare takeout orders. They ring them up under their own names, so at the end of the shift they are tipping the busboy on it even thought it wasn't a 'real' table. It still takes time to ring in and pull together the order so yes, you should give at least a few bucks for a takeout order.
Bands bring in bad tippers! (like kareoke nights) the person thinks 'I'm not eating so a buck will do' but that person takes up the table for 3 hours! 3 different times that table could have been seated!
The server is the last checkpoint before anything gets to the table. If a server hands you an awful looking plate of food, it IS the servers fault! It is her job to look everything over before it gets to the table. Same with drinks. If the food looks fine but taste's bad, THEN it's the chefs fault.
Keep in mind that even if the restaurant isn't busy that doesn't mean the server isn't busy! Servers have lots of tasks to accomplish from cleaning out soda machines to stocking glasses, silver wear, ice and sugar packets. They are not allowed to just stand around and wait till you need something! So when the restaurant slows down the manager starts handing out side work which usually cannot be done by your table. If she is in the back polishing spoons how does she know you need a drink refill? Yes, she should check frequently but she will get in trouble if she is just waiting around while you eat.
If you ever have a bad experience at a restaurant, complain to the manager. Several bad experiences, complain to corporate (if it's a chain). Your complaints and complements are heard and will get taken care of!