Medical and information network YourCity.MD has set up its own geo-targeted online ad network — what it's calling the largest such network in the US — spanning 450 cities.

The ad network reaches 215 million online users with an annual spend of $200 billion in out-of-pocket healthcare costs.

Per its Q3 2007 US Interactive Marketer Online Survey, Forrester Research observed that interactive marketers spend 20 percent of their budgets on geo-targeted ads. YourCity.MD hopes to draw such marketers with broad reach and low rates: up to 12 ads per specialty can be purchased across major US cities for 99 cents per day.