AppWatch lets you track new applications and repository activity, including:

repository history - list of applications being added, updated or removed from various repositories (even those not enabled by the user, e.g. testing and devel)
Hot Apps - list applications by download activity last week
App Forecast - show applications currently in QA, in order of expected arrival to Extras
App Stats - download graph of particular applications
Show a graph with the number of apps in repositories.