Ideally you should have a different password for every account.
Impossible to remember, of course - so now you need a password database. The danger in assembling your (different) passwords in a database is much lower than that of password re-use.

There are a number of good databases out there, from roll-you-own (Excel) to commercial and privately hosted, to web accessible. I'm a HUGE fan of LastPass ( https://lastpass.com )

The $0.00 edition is cross-platform, cross-browser, and dead simple to use. If you want access to all of your passwords on your tablet/smartphone, there's an additional one-time fee. Life got much easier for me when I started using LastPass.