My primary aim in setting up this website is to encourage that process: I'm therefore looking to publicise all GrappleThon events, not just the ones I run here at Artemis BJJ in Bristol. Please drop me a line if you're organising a GrappleThon/Grapple-A-Thon/Rollathon event and you want some publicity. I'll be more than happy to post the details on here, Instagram, Facebook, Twitter, tumblr, etc. This site is intended to collate that info, hence the plug-ins for Facebook and other sites to the right and below this text.
If you would like to run a GrappleThon yourself but you're not sure how to go about it, I've tried to collate what I've learned so far here: hopefully that will be of some use to you.