vmktree for VMware Server
vmktree is a free web tool that shows you the graphs of resource usage of VMware ESX 2 Server, VMware Server (on Linux) and GSX Server (on Linux). On ESX vmktree depends on vmkusage that is part of the VMware-esx-perf package, a utility from VMware that is included in VMware ESX Server 2.1.x and 2.5.x. For older versions it must be downloaded from vmware. vmkusage does not exist on VI 2 ESX 3. vmktree generates graphs as needed while vmkusage generate static graphs every five minutes.
If you are using CentOS 4 as your VMware Server host OS you'll need to install RRDTOOL first