I have a 250GB I pulled from my MBP when I replaced it with a 750GB HDD. I'm not sure what to do with it though. For the past year or so it's been sitting in a USB enclosure in my MacBook bag. It has a fresh install of Lion, but that's it. What do y'all do with them? It's the original Apple one. I guess it may be good to keep a working install of OS X on it in case mine crashes an I need to boot it up for some reason. I also have a 1TB HDD I use for Time Machine, so that's covered.