UPS
Calibration - Essential for accurate runtime estimation.
Alerting
I use Servers Alive - http://www.woodstone.nu/ for critical (and non-critical) notifications for just about any server or service on my networks. It has excellent newsgroup support. It is very customizable, and free for 10 or less alerts.
Brent Ozar - http://www.brentozar.com/ This guy has some excellent Server's Alive examples.
Here is a short list of things to verify on a periodic basis, some of these are automated, but they still need to be double-checked:
Verify File system defragmentation.
Verify antivirus full system scan
Verify antivirus updates
Verify proper folder structure on all production file servers
Check SMTP badmail folders and archive any IIS logfiles
Verify fans, LED's (Disk, network, power, error indicators, know your hardware)
UPSs check temperature
Verify system services
Disk space reports (I use Treesize pro, and run an excel report each night)
Print queues
Archive any old mailboxes
Backup Windows user profile, favorites
Check printers for toner leaks
Microsoft IIS servers, run a backup of the metadata
Any PC's not on the LAN: Windows updates, virus updates, virus full scan, defrag
Service Agreements / warranties - watch expiration dates
Software maintenance agreements - watch expiration dates
Internet domain names - Registration expiration, hosting service expiration
UPS Batteries - replace every five years