Maybe they save your screen, but flying toasters and shooting stars use a lot of energy.  Even plain black screen savers use energy. According to the EPA, using your computer’s sleep mode instead of a screen saver can reduce energy consumption by up to 70 percent.

The Green Team at the National Zoo asks us to use sleep mode or turn off our monitors when we aren’t using our computers.

On a large scale, ultimately (sleep mode and turning monitors off) could save enough electricity each year to power Vermont, New Hampshire, and Maine, cut electric bills by $2 billion, and reduce carbon dioxide emissions by the equivalent of five million cars.