How to to really irritate your successor sysadmin on a Solaris machine:

Set the machine's hostname not by changing /etc/nodename, but by hand-editing a 'hostname foobar' into the /etc/init.d/network startup script.

Of course, you won't want to keep the machine current on patches either; otherwise, your successor might take a much longer time to find this, and have a much less exciting day.

Important caution: for the safest results, insure that you are a long way away from your successor.

I must thank Solaris's patchadd and associated infrastructure for saving a copy of the old 'modified out from underneath it' init.d scripts; without that I might never have figured out how this machine had once worked.

(The modification was made right after the network script normally prints the hostname on the console, and it's relatively easy to find where that message is generated, so I can contort my mind to see how a sufficiently brute force sysadmin might set the hostname this way.)