What made you use throwaway email for this op? as I only use such for accounts I never cared much or willing to throwaway. If you're worried about exposing your email address, perhaps an email alias service could be of some use to you.

Perhaps you might be interested on password managers like keepass.info? this made things so much more convenient for me as I only need to remember one password to access hundres of my accounts lol. Plus your keepass database is stored locally and is encrypted. Passwords are also better off randomized though computer generated would be better than humans which fortunately, keepass also offers.