As you should all know, having the same password in a lot of different places is a bit of a security concern, especially when you register at a lot of different websites.
Most normal websites like this blog here don't use any form of encryption which means that your password is travelling unencrypted across the internet. Someone who is technically skilled could easily capture the password and some websites even save passwords unencrypted in their database, allowing the website administrator to read your password and gain access to your account.
Therefore, you should use different passwords whereever possible as it means that someone who gains access to one of your passwords won't be able to access other websites and ressources using the same password.
Unless your name is Data and you are serving on the USS Enterprise, memorizing hundreds of different passwords is definitely out of question. That's why some clever people invented password managers such as KeePass Password Safe, a free open source password managing application for Windows.
KeePass Password Safe, as the name suggests, is capable of storing several hundreds of passwords in an organized and safe manner. Usernames and passwords can be organized in groups. Each entry consists of a title, username, password, URL, notes and finally an "expires" field for timelimited passwords.
The URL field can be used to open a website associated with the password, to connect to FTP servers, to open SSH sessions or to execute programs on your computer.
Another great feature is the sophisticated builtin password generator. It allows you to generate complex and safe passwords by using password profiles or custom patterns for password generation. So if a website or software requires a password in a special format or doesn't support some characters, you can tell KeePass Password Safe how the password it supposed to look like.
The password database is encrypted using the encryption algorithms AES and Twofish. It can be unlocked with either a master password or a key file.
A portable version for USB flash drives is also available so you can carry your passwords with you.
Get it here: KeePass Password Safe