Here is a sample project which will show you how to send and receive JSON data from a WCF service using three of the most popular javascript libraries. You can do it without the libraries but why reinvent the wheel. Also, this is actually a VS2008 Studio Template so just download and drop the file into My Documents\Visual Studio 2008\Templates\ProjectTemplates\Visual C#\ and enjoy.
To use the template, goto File\New Project\Visual C# and look to “My Templates” and you should see WCF JSON.
The next step of course is how you display that data. Once again no need to re-invent the wheel 😉
Perhaps you might like to try the jQuery plugin called jsRepeater at http://jsrepeater.devprog.com/
… saves all that document.appendNode effort.