I mentioned the open source KeePass password manager the other day, but apparently there are a number of web-based password managers, including PassPack,and Clipperz. Clipperz also has an open source version of its software that you can download and then install on your own server.
I still think it’s easier and probably more secure just to use KeePass and keep the master password database on an FTP server so you can access it anywhere. Put the URL in your browser and KeePad will load it.