Yahoo! Voice has been hacked and 400,000 passwords were leaked. If you use Yahoo Voice then you should change your password A.S.A.P. Also, if you are using the same password on other websites and services, now it is a good time to change those too. Once again, the hack was based on SQL injection. Yahoo! has released a statement where apologizes for the attack to the users. If hackers have the password of your email account then they can access any other accounts where you used this email to sign up. Below there is a simple guide to create advanced and easy to remember password being different on each account.
Do not use the same password in more than one cases. If you want something simple to remember then you can use a base password and an additional letters or combination for each site. Lets say your password is password and you use the same for all the websites to remember then do something like this. On Yahoo! you can use passwordyh, on hotmail you can use passwordhm. Or to make it more complex to crack, password@yahoo and password@hotmail. Anything that will allow you to remember, make it more difficult to crack and be different on each website.