I really don't think we need to implement more measures to make the forums even less accessible. We want to capitalise on our traffic by making it as easy as possible for new forums members to sign up. The signal-to-noise ratio is high on most internet forums, but it's quite self-regulating in that those with nothing to offer get nothing in return and eventually leave. What remains is a slowly growing base of old-timers that are interesting.
The forums are a secondary service to the website itself, a bonus feature, designed to open up communication (and if desired, trivial banter) about Keira Knightley. Let's not be ignorant of the focus - General Discussions is not what the forums are about, although it's easy to forget sometimes. The last thing we need is a system whereby newbies must prove their worth as either a hardcore Keira Knightley fan (are they not all equally worthy of admiring her?) or sit some devious range of psychometric humour tests to pass a minimum entertainment quotient for the rest of the bored senior members.
In short: Not Gonna Happen. An interesting idea, and I'd like to see it discussed further. Sometimes we get gems in the shit.