Username and Password

What has been really troubling me lately is on all the websites username and password. To me its an absolute hustle and frustration. First of all is the username issue. Its hard to get a username for all the websites as some requires full email address and some username has already been taken up. The password is even more frustrating as it constantly forcing one to change password. How in the world are we going to remember tens of username and password, particularly if one need to constantly change their password and the old password cannot be re-used in the future? (Yes I am particularly referring to you- stupid Hong Leong Bank!!)