.ru is the most common locked in my spam filters...seems to be the same with everyone else as well. When i came into domaining i was told .info was a bad spamming extension...seems to have died off and now I'm an avid .info collector heh.....think i'll stay far away from .ru
The interesting part in a spam mail is not which e-mail address it is sent from as that can be any address. It has happened a few times that a spammer decided to use one of my domains in the "From" address. What is interesting is which SMTP servers are sending out the spam and which URLs are advertised in the spam messages. In general I do not get a lot of spam but Asian and American SMTP servers are the most common and .cn for the advertised URLs.