Is there any software available that you can run off a Linux distro such as CentOS that will allow a password database to be installed. Yet, allow the clients from like a Windows machine to connect to view them, requiring the master key to open it?

I have seen some called keepass (runs on Windows), keepassX and others but they appear to be only standalone entities.

What I am trying to find is a password database (running on a Linux distro) INTERNAL private netork only. But allow Windows, Mac and Linux clients to connect to it.

Does something like this exist, or has anyone setup anything like this using packages from the repository?

Any help/advice would be great.

The easiest approach (to me) when I see "must work with X, Y, and Z platforms" is to think web-based.

After a couple Google searches, I came across these two serverfault threads:
Password Management System for multiple SysAdmins? (which contains a reference to the thread linked immediately below)
Best Practise and Solutions for Sharing Passwords

In addition, there appear to be at least two projects on sourceforge that use PHP to address the problem:
phpPasswordManager (and the near-identically named)
PHP Password Manager

The second of those projects listed (the one with the spaces ), seems to be in "beta" and has a user-supplied comment that passwords with spaces are not supported. A little ironic given the only difference between its name and the first project's. But I digress...

If you feel up to it, you could always try to write your own. A simple database backend (BDB perhaps) with a PHP frontend is really all these solutions boil down to. If you have experience with PHP, you might be able to create a usable system in an hour or two. And perhaps an adequate system in a day or two.

Before the company blew up (good business), we shared a keepass database. Only one user can edit the database, but others can view in read-only and editing wasn't too frequent.

After the company expanded, a web-based app was developed. Much better.