I personally think this is a little kid having some fun.
This Bababada site requests your Yahoo! ID and password, which is troubling me. When I entered a fake password, it took me to the official Yahoo site (saying "Invalid Password"), but you never know what happened in between. If you work with Yahoo employees, I'd let them know that there may be someone who is trying to steal users' passwords on his site.
With those he could enter the site under thier names and cause a bit of damage I would think. I don't know how he would harm.
Last I heard Geocities and Yahoo were partners (if not owned by the same people). They could easily remove this site and make sure that no new ones open. They may also consider upgrading the login security or sending warning emails to users.
I checked one of the "cheat" links -
www.playbuddy.com/spade_buddy.htm
What they did there is created an application which somehow lets you cheat at the game. Needless to say, I didn't try it. The administrators can do a few things to counter that, however it works. I'd try to unleash the corporate lawyers at them first.