Contextual advertising company Proximic signed a deal with Yahoo Shopping and Shopping.com to advertise approximately 50 million items from their inventories. 50 million ads is a big inventory when you consider that Google AdSense is estimated to have only 1 million unique ads.

Proximic’s technology performs contextual matching based on the similarity of word shapes, supposedly a much more efficient method then matching keywords themselves. There is a Firefox add-on that demonstrates the technology by displaying relevant links and information based on what you are currently browsing.