suma -- Downloads your updates for you automatically and notifies you via email. It doesn't install them automatically.
Making your life easier
Nagios -- Incredibly extensible monitoring system. Can monitor anything you can write a script to check, and page you if things go awry. Makes you look like you're very on top of things, and has a very pretty VRML page that's not useful really, but it looks sexy when you show it to the suits. (VRML plugin available here)
OCS Inventory -- never have to go to a user's desk with your screwdriver again to find out how many free RAM slots their computer has. Never wonder just how many of those old Pentium III's are still lurking in the shadows.
OTRS -- Helpdesk package. To install on Debian 'apt-get install otrs2'. Yes, that easy. And an IT department without a ticket system is like...well....it's just bad. BAD
NTOP -- Detailed network traffic collecting and reporting tool, taking network sniffing to the next level. Great for finding weird traffic anomalies that are causing you headaches.
MRTG -- Graph any statistic you can get via SNMP. Great for tracking traffic through routers, room temperatures (with a device such as this, or for tracking disk usage on servers.
Wink -- for creating Flash-based computer tutorials. Tired of running through the same steps with all your users? Just make a Wink tutorial and plop it on your intranet or website, and email them the link! Or create a whole page of tutorials and point all your new users there!
Moodle -- open-source Course Management System. Featureful, and a dream to administer.
moveuser.exe -- change the ownership of a profile from one account to another. Does not move the files, only changes the ownership and makes that the new user's home.