How do I test a theme while coding it?

Is there a way to test a wordpress theme on my blog with out others seeing it? Like going to www.myblog.com?theme=<themename>? Or do I have to install wordpress in a new directory?

Thanks for your help!

 

Try this Joel:

http://wordpress.org/extend/plugins/theme-switcher-reloaded/

Another option is to install XAMPP and Wordpress on your local machine and develop from there. Much faster than doing it over the internet.

 

I use the Theme Test Drive plugin. It works very well.

 

Do you know how to do this with blogger? any offline tools to do this?

thanks

 

I like having wordpress setup locally using Xampp Lite.

 

Thanks everyone!

I am now using "Theme Test Drive" suggested by System0. It works fine for me online because I use Fling FTP so once I hit save, my files are uploaded automatically.