Related list clean-up

Over the years I've done a bunch of experimenting to try and repurpose modules to be a better fit for the business. As a result of this I now have a lot of custom related lists with the same or similar names, and I'm not sure where they came from. Any suggestions on the best way for me to identify the ones that are not in use vs. the similarly named ones that I am using, and delete the unneeded ones?