I blogged recently about my hard-drive failure and learning that my daily backup doesn't include the Operating System. Because I use Mac OS X - Lion there is no physical DVD to help get the OS re-installed quickly, instead you have to rely upon an Internet connection, and Apple ID.
Today I decided to upgrade the iMac at home from Snow Leopard to Lion, and I did a little Google searching to find just the article I needed, "Make a Bootable Mac OS X 10.7 Lion Installer from a USB Flash Drive." Using the details in that blog it showed me how to make a Lion backup and place it onto a 8GB USB drive. My local Staples store had a PNY brand 8GB USB drive for just $9.95 and it worked just fine for me. The whole process of downloading Lion, making a copy to USB, then installing Lion took an hour or so, most of which is waiting, so I could go off and do other things on my MacBook Pro.
Now I have a Mac OS X - Lion backup for when my next hard drive fails, which hopefully will be never. As the boyscouts say, "Always be prepared."