These are things I use on a daily basis and make my life somewhat easier.

Quicksilver
Mac OS X launch bar (among other things).

Subversion
Version control.

vim
Text editor extraordinaire.

nmap
Network scanner.

tcpdump
Network sniffer.

ditto_sync.pl
OS: Mac OS X
Updated: 2004.10.15
A very slow, and rather stupid, ditto wrapper for OS X. The comments in the script are very, ah, verbose. I'm not using this any more as we've migrated to netatalk2, which ceases to cause OS X to reboot during long transfers (yay).

harden_obsd.pl
OS: OpenBSD
Updated: 2004.12.29
A rather simple script meant to be cron'd to enforce certain file permissions and ownerships.

migrate_users.pl
OS: OpenBSD
Updated: 2004.12.18
A supreme ghetto-hack I kicked out in a few minutes to transfer the contents of the password file from a corrupted root disk on our primary mailserver to a new machine. It would easily be made more automated, but I'm not sure I care that much. The comments explain my reasoning.

resync.sh
OS: UNIX
Updated: 2005.06.07
A very simple backup script. Pretty self-explanatory. Written in shell.

.bash_profile
Updated: 2004.12.20
My very simple bash rcfile. Never leave home without it.

.screenrc
Updated: 2005.06.07
Added the shell directive. woot.

.vimrc
I think I've been using this same config for years now.

pf.conf
OS: OpenBSD
Updated: 2004.12.29
A simple pf ruleset. Needs to be cleaned up somewhat.

cvs-supfile
OS: OpenBSD
Updated: 2004.12.29
Place in /etc. cvsup is quite a bit faster than using simple cvs, I've noticed, so I try to use it everywhere.