$ uname -s
  OpenBSD

  $ uptime
  3:37PM  up 2597 days, 20:57, 1 user, load averages: 0.12, 0.13, 0.09

Though, uptime is only a measure of how long it's been since you last patched/did kernel upgrades.

This box is off most of the network and being left alone just to see how long it lasts before it totally dies ;)