A simple plugin to export templates in a .zip file and then install them from the same package in other servers.
After installing the plugin, you need to go to the "Export" subsection in the "Appearence" menu. Just select the theme you want and then click in the "Export" button. You will get a .zip file to download. Once you have the .zip file in your computer, you can install the theme going to Appearence/Themes/Install Themes/Upload in your wordpress administration pannel, and then select your .zip file and click on "Install now".