A repeater listing is only as accurate and useful as you make it - by adding any local repeaters to the repeater listing that are missing in your area, you are helping hundreds of app users browsing for nearby repeaters in Repeater-START.
If you manage a DMR repeater, the call sign listener can be integrated, letting others know when their friend or family member is on your repeater without leaving a radio on all the time. Currently the only guide for integrating this is available for the Pi-star software and is outlined on the blog here. Note that if you have a TGIF or Brandmeister linked repeater this may not be needed as those can have a callsign listener added directly from your dashboard.
Coding / Bug reporting
Are you a Python+Linux developer or an Android developer? Check out the Github repo where collaboration on new features and bug-fixing happens.