Protecting my server from it's own users [on hold]

Are there any tools to check my server's file system for permission vulnerabilities?

My server is a low security web and email server running our local email and website. Anyone in my organization can use the server, but currently I'm the only user.

I plan on giving user level access to people and I want to be sure that if they go playing around (perfectly ok), they can't break anything important, like conf files and such. In my case if a conf file is deleted I'll just recreate it, no money loss or anything, but I rather not have to spend the time doing that.