Hey Matt, in the gifting spirit, how about a link to the give-a-mefi-membership gift option somewhere on the Blue? Did the "beta" period work out? If so, don't be shy. It's a great feature. I just used it. But I had to hunt and peck through the MeTa archives to find it :)
Matt - speaking curiously, what is the system bottleneck that makes new users a bad thing? I presume it's database load, because the logged-in user enjoys comment counts and other database-intensive features that are demanding to serve. The static, logged-out homepage is easy to serve, even to a large number of visitors, by comparison, right? The real danger number to watch is the pageviews by logged-in users (please correct me if I'm wrong, I'm totally guessing). Are there features we could sacrifice for the sake of an open reg? What are you all willing to give up to open the gates? User comment history? Custom timezones and comment previews...?