grigori991

Plugin registeres simple widget within wordpress blog, that allows any visitor to change background 
color of theme. Actually it doesn’t change theme’s css file, but renders some style tag to user 
browser, that change the color locally. 
New background color associates only with user, that setted the color, and it tracks from cookie. 
So, if first visitor sets background color to ‘Rose’, second visitor can choose ‘Lime’ and third can 
leave that attribute to default and everyone get what they want at same time. 
If blog visitor sets background color to ‘Default’, browser explicitly deletes the cookie. Otherwise, 
cookie deletes itself after 30 days. 
Widget uses 4 ‘web-safe’ colors – #00FF00 (lime), #00FFFF (bluegreen), #9933FF (violet) and
FF0033(rose).

BGColor Setter

BGColor Setter plugin sets up the widget, that allows any visitor of blog to dynamically and graphically change the background color.

tommygeorge

Super Simple jQuery Parallax Background enables a parallax effect with your theme’s background image. Just set a background image in your theme’s “customize” options (optionally setting it to “fixed” position) and activate this plugin. Done. “It just works.”
It relies on jQuery, which comes with WordPress and is probably built into your theme. Tested and works with the “Twenty Twelve” theme out of the box.
Looks best with seamlessly-tiling background images.

Super Simple jQuery Parallax Background

For themes with background images, creates a parallax effect when scrolling. Super simple; no configuration. Just works.

BGColor Setter vs Super Simple jQuery Parallax Background