You can access the CLI by switching to terminal 1 using Alt-F1.
Now type “unsupported”, This is not echoed so you won’t see anything. If you get it right, you will get a prompt asking for the root pasword.

( This might not work in ESXi 4.0 as VMWare is trying to limit ESXi for their own corporate reasons )

That drops you at a shell prompt. (ash is our shell).
Hint: editor = vi

Now you can you modify /etc/inetd.conf and uncomment the ssh line so that you can ssh into it unless you are planning always being at the console.
Reboot (init 6)

Cloning Virtual machines in ESXi

vmkfs tools -i /vmfs/volumes/datastore/YourVM/YourVM.vmdk /vmfs/volumes/datastore/NewVM/newvm.vmdk

vim-cmd vmsvc/getallvms
vim-cmd vmsvc/power.reset xx

check out these ( with vim-cmd vmsvc/command ):

power.off
power.on
power.reboot
power.reset
power.shutdown
power.suspend

esxtop = is your top tool