Just found out about Apptrace, a new app tracking service currently in beta.
apptrace is the fastest app analysis service! Built by developers for developers. apptrace is maintained by an exceptional team of developers with extensive mobile experience. Giving you exceptional data, to further your business intelligence in the apposphere. It is the most efficient and intelligent way to trace apps on this changing global market.
So far I like the service and just registered for their weekly report. According to an interview with David Meyer from Gigaom, the App Store is currently "infested" with more than 400 000 zombie apps (apps that gets no download at all!).