Round about late 2011, I found that there had been log-ins to my Yahoo! mail account from foreign countries. Investigating, I found that they had logged in using some kind of mobile interface. I (thought I) disabled the mobile interface, as I read many reports of crackers getting into to people's email that way.
Today I logged in again and had a warning. Somebody had logged in a few days ago - again via Yahoo! mobile, which I thought I had disabled.
I had already been through all web services, etc., that I had registered with using my Yahoo! account, and changed them to another email account, on account of the last time it was cracked. For readers, I recommend doing this. Yahoo! mail is really not trustworthy.
However, for two or three web services I was unable to change the email address associated with it, so I didn't want anyone taking over the account. I also had a few emails I wanted to keep. So I didn't want to delete my account altogether.
What I did today was set up an account in Mozilla Thunderbird (an email reader) to retrieve all of my mail by POP, so it is stored locally but not accessible on the web interface. Now if anybody breaks in, they would have little information.