Where can I find vmkusage for ESX3.x?

vmkusage used to be a very nice VMware provided non supported application existed for ESX 1.5x and 2.x. In the beginning you had to download it seperately from VMware, but since ESX 2.1.0 it was included in the standard ESX install (but not activated).

When ESX 3 was released, a lot of things had changed. VMware also wanted a single point of operation and the performance stats in the Virtual Infrastructure Client had been much improved and was meant as a replacement of vmkusage. The result was that vmkusage was discontinued.

There are however free third party products that will give similar graphs like:
vmktree
unnoc

There are also a few commercial products:
Vizioncore vCharter
Veeam Monitor