Just as your Amazon Gold Box is full of stuff you'd never buy, most Web sites you visit are full of annoying ads you'll never respond to. Advertisers are reaching audiences, no doubt, but not necessarily the best targets for their products. The inability to control where ads appear or predict the content of the publisher's Web site is equally alarming. How do you find the best target audience for your online ads without going bankrupt? And how do you reach that audience without bothering anyone else?