I did it for a while, there was a program that parsed the yahoo pages, and converted it into a pop3 that it would send locally to outlook, ran third party, and was freeware.
It would also take your outlook outgoing mail (smtp) and send it off to yahoo via parsing it's pages.
There was also one for gmail, but gmail offers pop3 access now (for free), in fact, it might be the program the guy wrote that gmail offers on their site
Anyway, quick searching, i found this
http://yahoopops.sourceforge.net/
Yarr join teh New and Improved LoGD!