I use and recommend The Scuba Registry - Lost or Stolen Scuba Gear - Protect Yourself. Protect Your Gear. which is free for basic users (not shops or professionals though an Instructor can just sign up as a regular diver.) You can list all your gear along with a lost or stolen reports which send out a message to all members, etc. It is a great way to keep an inventory of your items. Check it out.
I love it.
I love it.