Discover Co-Registration Services - The Secret Weapon For Flooding Your Opt-In List With Subscriptions by Paula Morrow http://www.idealmarketingcorp.com It just wasn't happening. Yes, visitors were coming to the site, but the opt-in list was growing painfully slow. A new approach was called for, and a friend recommended trying a co-registration effort. And darned if it didn't work! With both free and paid variations available, co-registration is based on the practice of presenting a prospect.