It's all the rage on the Web these days: Design a program that creates a slide show, or shows on a map what countries you've visited. Then allow people to post these little add-on services to their online social-networking profiles, free.
Advertising companies are thinking of ways to use those programs to make money, a few cents at a time.
To a consumer, the process is essentially a quid pro quo. In exchange for using a widget, which might be a game or an interactive tool, a user must agree to allow the designer of the widget access to the information on their social-networking profiles. Ad companies can then mine personal data from the profiles and target their messages. So, for example, if someone says his or her favorite band is the Shins, that person is considered likely to buy a Shins T-shirt and music by similar bands.
I'm all for beyond-the-basics hypertext and compound/interactive document models, e.g., Traction TeamPage (this is getting deeply nested -- I just Googled "o'kelly traction" to find a link to a session I presented at the Traction User Group a couple months ago... and discovered I'm quoted in the Wikipedia entry on Traction), but the tulip-mania gadget meme-fest is getting annoying.
BTW you can find my hypertext and compound/interactive document model presentation from the 2007/09 Traction User Group meeting here (pdf). It doesn't contain any advertising-magnet gadgets :)