I was looking for a simple and secure way to store my passwords. There are many utilities available like Roboform, Password Corral, KeePass etc. I only tried KeePass and it works just the way I wanted. I can use it without installating it. Just download the zipped version, extract it on your computer and launch KeePass.exe. You can save username/password information in various builtin catergories called groups. You can also create your own groups and subgroups.
Read more about KeePass at http://keepass.info/