You can click the "Customize" link on any class home page to bring up the Customization window to add a variety of elements such as calendar, blogs, discussions, or even YouTube to a group space homepage.
(Note that this is different from the LMS Dashboard page, which has a fixed layout.)
Once you've opened up the Customize menu, you can click-and-drag to bring various content elements down onto the class home page.
The "Layout" dropdown menu at the lower-left lets you choose a 1-, 2- or 3-column arrangement for the elements on the home page.
After you've selected the elements you want, "Apply" your changes to close the Customize window. Each of the elements that you dropped onto the home page will have its own "settings" link that you can use to add content to it.
You can also clone your elements from one of your class pages to another. The "Copy" button at the upper-right of the home page (next to "Customize") lets you choose which classes you want to copy your changes onto. (Warning: doing this will wipe out any customization you might have already applied to those classes.)
Check out the Friday Folder Blog article on this topic, Home (page) Improvement.