I like SE-Screensavers and using it every day. Their product description says,
Enjoy animated slideshow or 3D photo album, fractals or matrix rain, dancing amoebas or kaleidoscope animation, fly over 3D surfaces, watch clock with calendar or growing forest with snowflakes. SE-ScreenSavers helps you relax and get away from everyday routine.
Sample screen saver pictures as below. If you like it download it here: SE-Screensavers or click on any image below.