I'm project managing a small design firm, and I'd really like to get a shared directory going - something that's Mail.app friendly.

When I add clients to my list of contact, I'd like the rest of my firm to have access to that contact information, and vice-versa. I don't want to sync all contacts across the board, just a directory of work-related contacts.

However, setting up a whole LDAP server is overkill.

Does anybody know of a hosted solution for this? Something that 5 - 10 people can use without going to the unnecessary expense of setting up our own LDAP server, configuring it, and managing it constantly?