Z2 is a ZZT archive founded in 2001 housing thousands of ZZT games. It is the only major ZZT archive, since ZA imploded. There are, at the time of this writeup, 343 registered users.
Z2 has helpful tutorials for newbies to ZZT, as well as several helpful utilities, such as ZZT Encyclopedia.
Just recently, the site went thorugh a redesign, and you can now log into the forums from the main page. There are 7 or so styles available, including the original (ie. pre-redesign).
When/If you submit a game, It usually gets uploaded quickly, and then up to ten people can rate it on a 1-5 scale.