Linux

The command to spin down the hard disk after 50 seconds (5x10) being idle:

/sbin/hdparm -S10 /dev/hda

When reinstalling an ssh server, one should keep the ssh key files from the old system. Otherwise ssh clients will receive messages of like "IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!". If you didn't keep the files, the clients can of course delete the entries from the host key file (usually /home/user/.ssh/known_hosts). When the user connects after that again to the server, the new, changed host key files are added to the host key file.

I have bought an iPod. And it appears that the 3rd generation iPod is substantially different from the previous models. E.g. in its file system. In previous models you could convert the HFS+ file system into a FAT32 filesystem. HFS+ is the filesystem used by the new MacOS X OS. It cannot be read by Windows OS (unless you buy commerical third party software such as MacOpener or MacDrive). There are several Linux-interfaces for the iPod, but they all require that the iPod is mounted as a regular mass storage device.