I just use the same one for most signups that don't matter.
If you crack my HotCopper password, you'll be able to post as me on bigfooty.com or the peugeotforums.com! Oooh, that's gonna hurt. You might get me moderated and I'll never be allowed to post again

There's some real incentive to make the effort.
But you won't get into my Ebay, paypal or bank accounts.