• by Erik Sass , July 12, 2011

The online radio business has been in a state of ferment over the last few months, with Pandora's IPO and this week's announcement from Clear Channel that it will debut a revamped version of iHeartRadio in September. They're not the only ones making big moves: Slacker has partnered with TargetSpot to power ads across its free online and mobile radio service, beginning with AOL Radio. Under the terms of the partnership, TargetSpot will deliver in-stream audio, video and display ads to AOL Radio listeners via online and mobile platforms, allowing advertisers to target the AOL audience based on personal listening preferences, time of day, and geography (at the ZIP code level) -- among other distinguishing characteristics.

The partnership covers AOL Radio's 250 programmed music stations, as well as its iPhone App, which AOL says has been downloaded over 3 million times.

AOL Radio joins TargetSpot partners, including the online audio properties of CBS Radio, Entercom, Live 365, Yahoo Music, and MySpace Music. TargetSpot claims to be the largest online radio ad network, with a total of over 950 online stations (including AOL Radio) and over 40 million monthly unique listeners.

TargetSpot's roster of advertisers has grown to include Coca-Cola, Toyota, Walmart and Budget Car Rental.

In January, TargetSpot announced that it had raised $8 million in a new round of funding from Union Square Ventures, Bain Capital Ventures, CBS Radio and Milestone Venture Partners.