1)   Performance Monitor 3.8.5
Monitor your CPU, Memory, Disk and Network utilization with this very useful program

 2)   PMP 8.0.1
PMP is a performance monitor for remote Windows servers. You can monitor the real time CPU, memory, disk and network usage values from the several networked servers and can be notified for specific server status.

 3)   UserTime 1.2.005
Record and analyze time spent on your computer! Monitor the time your computer has been running and the time each user is actively using the computer. Stopwatches record time for individual projects. Reports and graphs show a history of activity.