SolarWind has released a new VMware ESX Monitoring tool called VM Monitor. The new tool can monitor the status & utilizaiton of your ESX Servers as well your Virtual Machines. SolareWind VM Monitor uses the SNMP Service on VMware ESX to monitor your enviornment. As VMware ESXi does not support SNMP queries, it’s still not supported by SolarWind VM Monitor. In order for SolarWind to work with your VMware ESX you will have to enable SNMP on your ESX hosts. A good instruction on enabling SNMP on VMware ESX Host can be found at: VMware ESX How to enable SNMP.
Below you will find a good video of the SolarWind VM Monitor in action, please note the video cover a bit of SolarWind Orion product which is not a free product.
SolarWind Free VM Monitor for VMware ESX is nice & quite useful. I would suggest you try it out :).