You can always plug in a USB mass storage device and use the SD card as a readonly root FS, or even just /boot. And that's if the raspi can't boot straight from

You can always plug in a USB mass storage device and use the SD card as a readonly root FS, or even just /boot. And that's if the raspi can't boot straight from USB. That said my NSLU2 has been running Debian for years on a 2GB USB stick, swap included. There are a few Linux knobs you can turn to reduce writes a bit.