Need to upgrade? See if you can use OS X Internet Recovery!
Some of the computers that come installed with OS X Lion and above can use the newest feature Apple has introduced called Internet Recovery. This is a wonderful tool for newer computers (2010-present) to reduce the need for installation CDs and uses Apple's servers to install fresh copies of OS X or even perform diagnostics. Here is a list of the earliest computers that can use OS X Internet Recovery:
MacBook Pro (13-inch, Early 2011)
MacBook Pro (15-inch, Early 2011)
MacBook Pro (17-inch, Early 2011)
iMac (21.5-inch, Mid 2011)
iMac (27-inch, Mid 2011)
MacBook (13-inch, Mid 2010)
MacBook Pro (13-inch, Mid 2010)
Mac mini (Mid 2010)
MacBook Pro (15-inch and 17-inch, Mid 2010)
iMac (21.5-inch and 27-inch, Mid 2010)
MacBook Air (11-inch and 13-inch, Late 2010)
And unfortunately most cannot use this feature due to hardware limitations. Hopefully this quickxxcxc hint helps you out!
- The Doc