AWS security tool collections

I've come across a few of them lately:

• Jason Chan's list of AWS security resources
• Toniblyx's mega collection of AWS security tools
• Something that's missing from there: Brian Warehime's guide to Easy to use GuardDuty alerting with the help of Terraform and Slack

Edit 20-Oct-19: Configuring GuardDuty on multiple accounts is a PITA, so this article might help.