I was surprised to discover that it's very easy to install the VMware Tools on Windows Server 2008 R2 Core today. Simply select the VM in VMware Infrastructure Web Access (assuming you are using VMware Server 2, if not use the appropriate interface) and click the Install VMware Tools link. The iso won't autorun, but all you have to do is change to the virtual CD–ROM drive within the VM (probably D:) and run:
msiexec /i "VMware Tools64.msi"
VMware Tools Installed
