If you don't authenticate your account with something other than a password, they have programs for mobile phones as well as an authenticator you can buy to protect your account with. I got the keychain one before they had mobile phone authentication, (damn, it would have been cheaper), but it's still worth it. The last thing you want to do is watch a hacker get on your account, clean out every character you have, and sell your gold on ebay.
Hackers are the scourge of humanity, man. How pathetic is it that they can make money selling pixels. :-\