This tool saved my life today and avoided a ton of headache! What happened was that on one of my remote site which is completely out of my corporate network the IP of the Esxi host had changed.
I think when the people set this host up they set the IP on Dhcp rather than a static IP (ohh bugger!!), so anyway when I was trying to connect to it using the old IP I just could not get it working and was lost as to what the IP would have been changed to. The remote site is about 3 hours away so someone would have had to physically drive down and plug in a monitor and tell me the ip on the screen!
So I came across a tool called ESXi Host Finder in which you can give the subnet that your host is in and it scans all the devices in that network and returns the ip's which possibly could be of a host and when I did this I was able to identity the changed IP!
So in case you are in the same situation as I was or probably even a different one you can use this tool to identity your esxi host on a given subnet!