I don't know about having to get an email account before joining a group. I already have a mail account there that I use for website registrations only. As for putting stuff on your machine or comparing it to the damnable Cool Web Search, never seen it happen. Yahoo's just another web portal as far as I've ever experienced. I've never installed any of their extra little goodies though.

"Democracy is a pathetic belief in the collective wisdom of individual ignorance." - H. L. Mencken