Windows: With luck, blue screen of death is something that most Windows users don't see anymore, but if you do, sometimes it can go by so quickly that you don't get a chance to review the error displayed so you can look it up later. BlueScreenView is a free utility that will retrieve the error information for you later so you can research what caused it.
In order for BlueScreenView to work, you'll need to make sure Windows is configured to save crash information to your minidump folder -- that's where the app goes to look for it. (In Windows 7, this is in System Properties, under "Startup and Recovery" in the Advanced tab.) Then, once you've restarted your computer after a blue screen error, you can open BlueScreenView to see what driver or module caused the error, what the error code was, and even perform a Google search for the error right from the File menu of the tool.
With BlueScreenView, you don't have to scramble for pen and paper if your system crashes: you can reboot in safe mode and search for what caused the error quickly. BlueScreenView is free, and supports all versions of Windows, including Windows Server 2003 and 2008.