Type "screensaver" into a Web search box - go ahead, I dare you. What you'll come across is a number of scamming, ad-filled, useless sites that care more about lining their own pockets with revenue than actually delivering you the goodies you want for sprucing up the look of your system's display. I can't help you much there. The appeal of a particular screensaver is, after all, in the eyes of its beholder. You might like flying toasters; I might like ports of OSX screensavers. There's little point in me trying to push my tastes on you via some freeware roundup.
That said, there are a number of interesting applications that can help you better manage your display. Regardless of whichever screensaver you choose to use--including none--the freeware tools listed below will let you best manipulate your screen to your liking. Enhance your daily computer use with increased energy-savings or prevent annoying interruptions to your media-watching, amongst other tricks. And, yes, you'll even be able to turn your screensaver on and off at a whim...