There is a free, Catan play-alike at games.asbrian.com called Xplorers.
Asosbrain requires free registration (you don’t need to give them your e-mail)
It requires Java 1.2 (you can go to http://games.asobrain.com/faq/start.php to check)
I would be interested in either a standard or Knights and Cities.
I’m free tonight (JUL 22), but am guessing it is too short of a notice.
I love Catan but have found that computerized versions either don’t account for loopy trades, or if they do, the mechanics are tedious. When I play with buddies, the trading phases are miniwars in themselves, with all kinds of nutty deals offered and accepted at NYSE pace. We play Civilization the same way.
I’ll make a note of the Catan site and if you see a player named “BryanEkers”, that’ll probably be me.