Sponsorships are growing as an advertising concept and the most interesting sub-segment is the one where consumers select the sponsors they want to be associated with. One of our companies, AWS Convergence Technologies (the folks behind WeatherBug) was a pioneer in this space. They even pioneered the Sponsor Select Network, which opens this for third parties.
An interesting twist to the model comes when you combine it with social incentives. The latest arrival (I saw the news in PaidContent today) is ArcheType Media / SocialVibe. They let brands sponsor your social network profile. Here is an example (on their site and on MySpace). The bait is doing good and getting goods.