As of now, you can provision the StatsMix add-on for your AppHarbor applications.
StatsMix is a great way to track events and actions in your application. Even better, StatsMix is a powerful platform for visualizing data and using charts and dashboards. Metrics and dashboards can be shared via email, public urls or embedding.
To start using StatsMix on AppHarbor, simply add the add-on to your application. This will make a
STATSMIX_URL configuration variable available to your application. Use this when interacting with the StatsMix REST API. John Sheehan has a good Gist demonstrating how to use StatsMix from .NET with RestSharp.
StatsMix also maintains a NuGet package and there's a .NET documentation page on their site.