Businesses spend $16.3 billion a year on trade-show trinkets like those personalized pens, key chains and letter openers that are probably sitting in your desk drawer right now. That's because they work, says the Promotional Products Association, which represents the companies that make and print all that wonderful stuff.

The trade group hired a research firm to buttonhole business people at airports to find out what they thought about the giveaways. One in three actually had an item with him. Roughly 75 percent had received giveaways, and almost 80 percent of them remembered the company that gave it to them. Compare that with the 47 percent who couldn't remember any advertiser in the newspaper they had read that same morning.

The most popular stuff these days? Memory sticks--those removable USB-port hard drives--and just about anything else related to tech, like laptop lights and cell-phone covers. In order for a giveaway like this to work, "it really has to be useful," says Bill Prickett of the trade group. Just like all that other stuff in your pocket.