Varying passwords for each service without memorizing

It's a good practice to use different passwords on each single service you use so that if one of the services is compromised due to any reason, the hacker is not able to hijack your whole internet identity. Such a practice might come in handy for those changing their passwords in wake of the heartbleed bug.

There can be quite a few ways to do this (and you can invent your own as well, share in the comments if you like).

1. Categorizing:

Categorize your passwords for each type of service. A unique password for the primary email address (which you should change every now and then), a single password for the social media (Facebook, Twitter, whatever-you-use etc) and another password for, for example, your secondary email addresses or your work / academic addresses. This method categorizes different types of services and protects you from anyone who has found one of those passwords from moving on to other types. Something of the sort done in space stations and submarines; section wise protection so that even if one section is breached, others remain safe.

2. Variation:

If you find even categorizing difficult to memorize you can go for this method. To vary passwords, you can choose a formula that bases the variation on a theme. Decide a core password of a mixture of six letters and numbers (alpha-numeric) that are not any dictionary word... say xYz123.

Now, all your passwords for different websites or services can be variations on that core password, and you don't have to remember a separate password for each service and yet actually use a different one for every single one of them.

For example, you can pick the last two letters of the service's name, so that even if your password is viewed or compromised one can not tell what the ending letters are, and place them at the start and end of your core password. So if you are using Gmail, the letters are “i” and “l" which come at the start and end of your core password which would now be ixYz123l. For Facebook, your password would be oxYz123k ("o" and "k" - the last two letters - at start and end).

You can, ofcourse, make this a much easier variation by just adding them to the end of your core password or, perhaps, make even more obscure by making your variation formula / scheme more complex and adding the letters somewhere in the middle or at two places of your core password. Depends on how good you are with words.

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And on top of all, it is always better to keep a unique, unrelated, password for your primary email address so that there's always somewhere you can go and use a "forgot my password" option making it your last line of defense.