I would probably write a custom web-based solution hosted on a corporate intranet. (take a look at http://lastpass.com for inspiration, or to use it. Sharing passwords is one of its features, though it may not work for your volume.)
EDIT: Sure, best solution, don’t share them. Storing cleartext passwords in any medium is dangerous, particularly when the purpose of storing them is to share them. There is a nearly infinite number of solutions, each bringing an associated peril. Why not put them on an encrypted disk image, burn that image to a single CD, put the CD into a safe that only one armed guard can open, and have authorized people present photo ID to have it unlocked?
The point is we don’t really know your scenario. Why are you sharing hundreds of mission-critical passwords? Are they for your backoffice intranet, VPN, or are they customer passwords that you keep around in plaintext for some reason? Are all the people you need to share it with in the same installation? Would a physical transference like an encrypted CD or a printed table stored in a safe actually work? Or are your sysadmins spread over the globe, making electronic means of sharing them the only solution?