I met one today. Spot Runner.
Spot Runner can create TV commercials for a fraction of the cost of a large agency and then geo-target the commercial to the right audience in the right location. Their customers tend to be small local and regional businesses that cannot afford TV using traditional means, or orphaned brands within large consumer product companies. The entire transaction is done through Spot Runner's website. (Yes, we're in an era where the client/agency relationship can be described as a transaction.)
The collaborative opportunities within the frenemy relationship are using Spot Runner to support local dealers and franchisees with one-off tactical promotions, or perhaps for test marketing ideas before investing in a large-scale campaign.
Will Spot Runner put advertising agencies out of business? Thankfully just the really awful ones. Not to be overly Darwinian, but the herd could be thinned a bit