Wow, I could have used that feature as my forums are restricted and require approval. I added an extra field in the registration form labeled "Codeword." Anyone I invited was given a codeword that I change from time to time. The idea was to give me a reminder and confirmation that I invited that person. Your suggestion takes it one step further and automates the process... I would still want to review these people but such a feature would be useful to some people I am sure!