I recently started working on a remote debugging/monitoring tool for Racket programs. It comes with a TCP server for exposing debugging information, a client implementation, and a GUI that builds upon those two things. You run the server as part of your application and then connect to it via the UI to debug things. Currently, it provides insights into GC pauses, current memory usage by data type, and a way to run and visualize performance profiles.
Below, you can see a short demo of dbg in action. The library is available on the package server and you can find the source code on GitHub.