Mobile M&A activity continues … except this time it’s a mobile ad network on the buy side. Following Google’s $750M AdMob acquisition, and Apple’s $275M Quattro acquisition, the largest remaining independent ad network, Millennial Media, will acquire mobile analytics firm TapMetrics for an undisclosed amount.

TapMetrics will allow Millennial to offer developers more comprehensive revenue management dashboards. This will be chock-full of application analytics such as feature and version adoption, device access types, user feedback, and crash reports.

Overall, this can be viewed as a very developer-centric move. As ad networks increasingly compete to build networks of app developers, this will help Millennial to provide better incentives. The carrot for developers here is a tool to better optimize and monetize their apps.

Speaking of analytics, this is a good chance to mention Millennial’s latest in its line of monthly SMART reports. It takes a year-end look at some of the biggest trends and lists of ’09. See the collage of data below and download the report here.