Got tired of the standard netsaint disk check plugin, so I wrote my own in perl that checks every disk on a system. Then I added in excludes, so you can exclude things like /mnt/cdrom.
Then the junior admin pointed out that sometimes we'd end up excluding more directories (nfs mounts, cdroms, etc.) then we were checking in the first place. So I wrote a new plugin that accepts includes and lets you check multiple disks that way.
Then I thought to myself that all of that was silly, so I rewrote the plugin to accept both includes, excludes, or neither (which will check all of the disks), and to allow perl regexs for both includes and excludes. Ahhhh... much better.