jsPlumb is jQuery plugin that allows us to connect elements on the screen with “plumbing”, using a Canvas element when supported, and Google’s ExplorerCanvasscript to support older browsers. It’s written as a jQuery plugin, and relies on jQuery 1.3.x or jQuery 1.4.x (tested on 1.3.2 and 1.4.2), and also jQuery UI 1.7.2 (if you want to support dragging). For Canvas support in IE you also need to include Google’s ExplorerCanvas script.

http://blogfreakz.com/jquery/jsplumb-plumb-elements-of-a-ui-together/