My first ever email address was my employee number: TX1941. Now I have about 20 different user names and pass words. Every thing from the bank to the phone company to the pizza joint wants an "account", and remembering all of them is a pain. When the only computers I used were on my desk at the office or house, I could write them down and find them when needed. Not so much anymore.
I try to make my passwords as secure as possible, but I often use some variation on that original email address for my user name. At least I can remember it...