Static — Analytics for iPhone
I use FeedPress to provide the RSS feed for my site. Although they have a decent responsive page for checking subscriber stats from my iPhone, it can be a little difficult to interact with sometimes (particularly the subscriber graph). A native iPhone app would be more preferable, and today I got my wish with the latest update to Static.
It tracks statistics from all sorts of services—Facebook, Twitter, Google Analytics, and more—but for me the most important feature is its FeedPress dashboard integration. Static ties into the FeedPress API to give you a nice readout (including its own graph) for your RSS subscriber count, as well as a breakdown of the RSS services used to read your site. You can see what it looks like in this FeedPress blog post.
Static is just $2, and there's an ad-supported free version as well, if you'd like to try it out before buying.