Ad Networks, CPMs and Fill Rates
I spent the afternoon rearranging/verifying the ad network chains across the gawkerverse sites. We started out with just Martha's Circle and Platefull in 2008, but with their fill rates dropping, we've added more networks each year.
The non-exclusive networks that we've used and seen the best CPMs have been...
1. Federated Media
2. Platefull (fill rate has been very low this year, only 19% YTD)
3. Martha's Circle
4. Burst Media (33% fill rate YTD)
5. SustainLane (fill rate is terrible, only good around Earth Month - April)
8. Google Adsense
The YTD fill rates across networks ranges from 19% - 35%, but we are seeing fill rates as low as 3% this summer. On some ad slots, we have seven ad networks in the chain, but it's typically 3 - 5 networks chained per ad slot. Ad chaining helps us maximize revenue, but the downside is the additional ad loading time, especially if the networks at the top of the chain aren't filling.
I've also looked into ad optimization solutions (Admeld and Pubmatic), but I'm early in this process. Lijit (who uses Admeld) is simple option if you want to fill your ad inventory and don't mind seeing a lot of non-endemic ads.
For ad serving, we use DFP Small Business...http://www.google.com/dfp/info/sb/index.html
which allows us to traffic any directly sold ads. The only thing we don't like is the ad scripts for DFP are not asynchronous and does block page rendering.
Anyway, that's been our experience with ad networks over the last 3+ years. Let me know if you have any ad networks that you like and would recommend using.