We have one particular server that's hosting many of our databases, NFS for our internal software distributions etc etc. We reboot it a couple of times a year to get kernel updates and such. One of those times is in a minute (so a short outage of some services will occur). Crossed fingers it'll come up alright, we don't want to go to the datacenter right now. :-)
update: eek, it's not coming back. crap.