App development will probably be slow for a bit. As others have mentioned, Artemis is in development, but because Kbin doesn't have a public API yet, I believe that Artemis is having to use their own web scraping method as a stop-gap until the API is released. I imagine that's probably a taxing process for the dev's server to handle, which is probably why the private beta is having such a slow rollout.
Once the API goes live, I imagine there will probably be several apps that pop up pretty quickly.