My normal use for the SD card slot is different and many people would think it was a crazy way to do things.
For school work I do dual booting with Windows 7, and choose not to install software to make the other partition writable. All my current school work is saved on a 1 GB RS-MMC (card) that is semi-permanently left in the slot. Because the RS-MMC cards have a detachable extender, that can be removed while the card stays in the slot, nothing sticks outside of the computer to get bumped or broken during travels. These cards are discontinued but you can still find some on a few online stores.
http://en.wikipedia.org/wiki/MultiMediaCard#Reduced-Size_MultiMediaCard_.28RS-MMC.29
It is also included in my backup-plan just like any other drive with important files.
So there is another (strange) usage for the SD slot.