Rex Wong, the former CEO of Applied Semantics -- a company acquired by Google specifically for the technology that would end up creating AdSense -- has launched Dave.tv, (yet another) video aggregator site. This one, though, will utilize "audio keywording" -- i.e. serving up contextually relevant ads based on the words heard in the video. Business 2.0 explains:

In other words, right now the inventory for video ads is limited to two spots per video—one before and one after. But imagine if a computer could identify when somebody said "shampoo" or "burger" across millions of videos, and you could insert a text ad for Prell or Wendy's along with a clickable logo graphic next to the video when those words are spoken. If audio keywording actually works (and I did not see a demo of it, so I don't know), it could be huge. Because then you'd have a heck of a lot more ad inventory to sell.