DiskMonitor is a powerful tool that enables systems administrators to centrally monitor disk drives. It automatically enumerates available networks and allows you to select disks to monitor and shares to iterate (admin access required). Critical and warning thresholds can be set. When the thresholds are crossed, it can send a detailed message, a PDA friendly message, or a user defined email message to any set of users.

download: DiskMonitor v7.0.0.30