Liferay 6 offers feature of Site Templates , where in you can design a site template . Using the newly designed template you can create multiple communities and organization on the fly. Just apply the template  while creating those communities .

Site templates is nothing but a community which will act as a template for new communities. It will have Pages , Portlets , Content just as a regular community can.

Here are the steps to create a site template and create a community using the newly created site template.

1) Login as  admin. Go to Control Panel -> Site template

2) Create a new site template.

3) Go to Control Panel -> Site template ,  Click Actions (for the newly created template ) -> Manage Pages  to create pages in the newly created template.

4) While creating the pages , you can also use the Page Templates to create a page without any efforts.

Refer this Post. Page Templates

5) Once the page creation is complete. You can browse the template as regular community.

Control Panel -> Site template.  Click on template . at the bottom you will see  Open Template link.

Once the template is open , you can modify it as a regular community.

6) Now we will create a new community using this template.

Go to Control Panel -> Communities . Click on ADD button to create a new community.

While creating the community you will get the option to select the  available templates.

Select the one which we created just. Click Save to Save the community

8 )  Now you can browse the new community. Which we created using the site template.

You can use same template to create multiple communities also.