The name says it all, it is a graphical version of esxtop which can be run on Microsoft OS, Linux OS and on Mac OS** so it is really "cross-platform".
It works remotely and can be run on any computer which has network access to ESX(i) host or vCenter (although I haven't been able to connect it to a vCenter successfully).
When you run it, it looks like a enhanced version of esxtop
It will color coat important counters and issues automatically. Further more it has the ability to record and playback batch output, it can create line charts for selected counters and it has counter descriptions when you "mouse-over" them.
To download this Fling, which I recommend as it is a very useful tool to have please go to VMwareLABS
** As said before it is cross-platform, but to get it to run on Mac OS you need to take some extra steps. For details on how to do this please read How to Run VMware's New Fling VisualEsxtop on Mac OS X from the virtuallyGhetto blog of William Lam