With a number of broadcasters already on board, TargetSpot is rolling its radio ad marketplace out to all, reports ClickZ.

TargetSpot delivers ads to streaming audio that come as pre-roll or in-stream ads of various lengths. Those spots come coupled with banners that appear in the media player, allowing for more user interactivity through a visual call to action.

CBS Radio, WarpRadio and Entercom Communications have, in total, given Targetspot access to about 350 online stations at the time of launch. Advertisers can target spots by station or user geographic/demographic information.

Off the bat, TargetSpot will be able to sell time within 20 percent of a station's streaming inventory. That could go up later, based on performance.