Which command-line packages do you need? I generally have one of Fink, MacPorts, Homebrew installed. Most often for a single, small, and trivial package. I've found that all my day-to-day software exists in OS X versions.

So, which non-OS X unix software do you find is required, interesting, or otherwise always on your computer.

I'm looking to broaden my horizons. I have enough unix/linux experience to not be afraid, I just haven't found a good use-case yet.

For added clarity, I'm not looking for anything already installed with OS X. So, please, no ssh, vi, etc, unless you explain the reason you need a different version.
I frequently reinstall MacPorts (e.g., when there's a new major version of Xcode) so I keep a file with a list of my essential ports for easy reinstalling.

Here's my list of essential software that doesn't come with OS X.


arping
dnstracer
watch
wireshark
figlet
gnupg
ipcalc
lynx +ssl
minicom
mtr
ncftp
nmap
pstree
pwgen
p0f
sipcalc
ssldump
stunnel
tcpflow
unrar
w3m
wget
wordplay
fortune
cowsay
ack