We have recently been experimenting with various ad providers to better monetize our apps. Originally we used Airpush as the main ad provider, this included banner ads, wall ads, home screen icon ads and push notification ads. Airpush was a decent source of revenue (about $5 a day) however icon and notification ads resulted in many negative reviews and had to be removed from our apps, these ad formats have since also been disallowed from the Google Play store. We still use Airpush but only there banner and wall ads.
We trialled AppBrain and included a banner ad and an app exit ad which was very easy to install. These ads yielded several clicks, were not intrusive and the AppBrain Apptimizer tool was very handy, however the revenue earned from AppBrain was rather low, in a period of 2 months the revenue earned was: $8 in month 1 and $9 in month 2.
As AppBrain was not providing the desired revenue we decided to replace them with Google Admob, utilising the Admob Smart Banner and Interstitial ad formats. So far the results have been positive and as we have just integrated we will post back some revenue figures in a few weeks.