Experiments 3 and 4 are now up and running concurrently.
http://xvams.com/xvams/The next few people to make a username will find one of each set up and waiting. There's no big hurry, but please only start if you're going to finish. I'll follow people up every few days or so if experiments are not being used.
Started.
Thanks.
I'll let you know my payment address once I'm done.