Vote for VM Monitor
SolarWind's VM Monitor is a small (4MB) free tool that, using SNMP, quickly shows you the status of your ESX Servers including: Version of ESX you are running on the ESX Server CPU, RAM, and Network RX/TX utilization Number of VM Guests running on that server VM Guest performance including CPU, RAM, and Network RX/TX utilizationAll of this information is shown very quickly and is visually appealing - running on your desktop, similar to a Windows Vista desktop gadget.