I know this is beating a dead horse, but encrypting your user's passwords is one of the most important things you should be doing. Failing to do so shows a complete lack of respect for your users, and demonstrates that your site/service is probably not worth using.

There should be a list of companies/sites that don't encrypt passwords, so we know what services to avoid. That way, next time you use the Forgot Your Password feature and they email you your plaintext password, you can add them to the list to warn others.