BuddyPress.org

Shouldn’t be too difficult to hook into the user’s BP settings tab and have a drop down box that allows them to select the various components as the front page. Have the drop down box save the component slug (so ‘forums’ for the Forums, ‘activity’ for the Activity stream, etc) and then you should be able to just use that slug in the locate_template call in your new page template that you created.

Something like:

<?php locate_template( array( $user_selected_component.'/index.php' ), true ); ?>