If we must have unrestricted signups, then we should require either a verified ID or a verified sponsor to leave Orientation Island.
What I am proposing is that LL provide some sort of buffer in which an un-verified new Player gets a taste of SL, but remains isolated from most of it until they prove they are 'civilized' and of legal age. In fact, a more prolonged stay on orientation island (or a small collection of sims that are all the new accounts can access, but which existing accounts can also get to) might not be a bad idea for all new accounts...
An example that works elsewhere: ****************************
I have served for several years and still do) as an admin and new member greeter for an RP forum that allows "open signups". The application for a new account asks for real world personal info (name, e-mail, etc.), but doesn't require any more actual verification than the current open SL registration does. It just gets tracked by the e-mail address that you give, and it does do a verification that the e-mail is at least valid.
They have a very simple method for keeping out troublemakers. All newly created accounts are restricted to an "enter forum", essentially like the Orientation Island in SL. The new accounts are expected to interact there in a civil manner with each other and with established members who visit that area, and to learn to "play the game according to the rules" while there.
To leave that area and play with everyone else, the new accounts must meet one of the following criteria:
A: The account is an acknowledged alt of an existing registered Player. They make a request in a publicly visible forum thread from their existing account, for an admin to authorize full access for the alt. That admin checks the existing Player's behavior, and if they are obeying the rules, the new alt account gets full access. The administrative records (not publicly visible) show who is associated with that new account. No time limit. They could get authorized the same hour the account is created, if the admin is available.
B: The account is an non-acknowledged alt of an existing registered Player. For whatever reason, the existing Player does not want the general public to know this new account is their alt. There are valid reasons for this, such as wanting to have this character play a special RP role. They make a request via e-mail from their existing account to an admin to authorize full access. That admin checks the existing Player's behavior, and if they are obeying the rules, the new account gets full access. The administrative records (not publicly visible) show who is associated with that new account. No time limit. They could get authorized the same hour the account is created, if the admin is available.
C: A new account has existed long enough to make 30 posts in Enter, interacting with other people in an acceptable manner, and has been sponsored by an existing Player. Someone who is already authorized observes the new character in the enter area, interacts with them, and decides they are willing to vouch for their behavior. That existing account makes a request in a public forum thread, to sponsor a request for an admin to authorize full access. The existing account takes responsibility for the behavior of the newbie. That admin checks the existing Player's behavior, and if they are obeying the rules, the new account gets full access. Requires a certain amount of time in the system, behaving in a civil manner, before they can be authorized.
Bottom line: You don't get past the entry area if you are being a jerk, or are not willing to behave in a civil manner. Those who act unacceptably while in the Enter area lose their shiny new accounts. If you do get past the entry area, someone has taken responsibility for your behavior.
If someone in those forums breaks the rules, there is a very good chance that they and all their alts will get banned, weather those alts are acknowledged or not. That forum is VERY serious about dealing with rules violaions.
End of example ****************************
Taking this parallel to Second Life:
To get off Orientation Island, you do one of the following:
A: Provide verified ID in some form. Credit Card, "Adult Check ID" membership, a tangible postcard that has to be mailed to a postal address and returned via mail to LL's offices... Provide some sort of tracable ID for that account and the others that you own. This could be as simple as notifying a LL Admin "Hey admin. 'Bob NewAccount' is my alt, I take responsibility for what he does. Please authorize him."
B: The new account has spent at least 30 days on Orientation Island, and has no complaints lodged against them. While they are there, they provide a mailing address, and an ID verification card is mailed to them. They sign it and return it, probably also providing some other sort of identifying information.
C: The new account has spent at least 30 days on Orientation Island, and has no complaints lodged against them. While they are there, an existing, verified member can sponsor them, with the understanding that if this new account breaks the rules at any time in the next 30 days, the Sponsor is liable for the newbie's actions, and subject to possible disciplinary action themselves.
OK. Let's discuss this. What is a reasonable waiting time? Should additional sims be added as a step between Orientation Island and the rest of SL, where existing, verified accounts can meet with and interact with the new people? What should be required to verify identity? Bear in mind that this is an International community. Not everyone has social security cards, or driver's licenses, or some other standard for an ID card. What can we do that would work for everyone?