1. Send them home DIRECTLY.
On any given Saturday or Sunday, you can find couples out shopping for major appliances. They'll go from one appliance store to another looking and checking prices. There is some school of thought that they will buy from the last store they visit (if not immediately, eventually). One appliance store I heard about makes SURE their store is the last one a couple will visit. After they've visited with the salesperson and are about to leave, the staffer goes over to the store's freezer, takes out a half-gallon of ice cream and gives it to the potential customer. Nice gift, of course; relates to a major appliance, of course, but the couple now HAS to make a beeline for their abode.
If you are a retailer on a street with parking in front of your store, you might try some goodwill generation like this. One store I know keeps an eye out the window for any expired marketing meters in front of their shop. When they spot one, they go out and put a dime or two in the meter and a note on the window saying they did so. Can't help but make friends AND get that driver talking to his/her friends.
3. Make-Believe For Success.
As the saying goes "excellent restaurants don't have to advertise." Well, maybe. But you don't start a restaurant with so much business that you don't have to promote. One guy, however, turned the tables on this premise and reportedly it worked. He started his restaurant, did a little promoting, and when the phone began to ring he said something to the effect, "I'm sorry, we're just too busy to take reservations, please call back." He actually wasn't, but he wanted to build the impression for the long run. Gutsy or nuts. You decide.
4. A Doozie.
When you REALLY need people to show up somewhere on time, and you are the one calling the meeting, here's a doozie. Send EVERYONE you want there a key with a note saying, "I'm going to be late, please open up for me a few minutes in advance." Sneaky isn't it. I really like it though.