If a person clicked on the ad, it would prompt the user to download or use the Expedia app to book the transaction.

WSJ: Online Ads Can Now Follow You Home

For example, the company recently developed a campaign for Electronic Arts that was able to target Xbox 360 owners with an interactive ad for NCAA Football '11 that allowed them to download a demo of the game to their console.

FORBES: Magazine Article

When a user clicks through a Williams-Sonoma ad to browse, that user is not only prompted to download the app but also to register as a customer so they can pick up shopping where they left off.

FORBES: 3 Lessons Del Monte Can Learn From Playing Fruit Ninja

Making it easy to discover and enjoy new music, Nokia Music provides free streaming of ad-free tracks without registration or subscription and the ability to download playlists for listening offline.

ENGADGET: Nokia Lumia 620 announced: 3.8-inch WVGA display, 5MP camera, $249

Jivox, a small digital ad company in San Mateo, Ca. creates ads that, when clicked, download coupons and give store information.

FORBES: Inside the Stupidity of Display Ads