Look on CodeCanyon there are loads of great plugins for site templates and for WP that do this. Good luck
Best one is SlidePanel—http://codebomber.com/jquery/slidepanel/
As a mobile menu, works in simple browsers also – jSlideMenu
Some CSS3 magic – Meny—http://lab.hakim.se/meny/
Web-Kreation jQuery Panel—http://web-kreation.com/all/nice-clean-sliding-login-panel-built-with-jquery/
Web-Kreation MooTools Panel—http://web-kreation.com/tutorials/nice-login-and-signup-panel-using-mootools-12/
jQuery Side Content—http://www.stevefenton.co.uk/Content/Jquery-Side-Content/
Here’s an example. http://www.dtelepathy.com/ Look on the right side of the page (the plus sign). When you click it it comes out. Anyone know what this would be called or where I can find a snippet somewhere?
Off-Canvas is the Word you’re looking for. Foundation by Zurb has something like this included but also some of the links from campuscodi are very interesting. Especially the jpanelmenu got my attention.
If you are looking for a wordpress version, you can check this onehttp://codecanyon.net/item/gilidpanel-wordpress-sliding-panel-sidebar/5753924