Is there any smart way to set a site (blog) as a master, which settings are replicated to the rest of the sites in the network?
There are plugins like this one: YD Network-wide WPML that attempt to accomplish this, but they don’t support all settings.
There are two options I’m aware of, and neither are free:
http://premium.wpmudev.org/project/new-blog-template
http://wpebooks.com/replicator/
I haven’t actually tried either of them yet, so can’t recommend one over the other.
there is http://wordpress.org/extend/plugins/default-blog-options/ too.. but its not working for custom post type or taxonomies..
With this plugin it’s possible to duplicate everything from a site of the network to a new one.
http://wordpress.org/extend/plugins/add-cloned-sites-for-wpmu-batch/
I use it like this:
Yet another option to consider:
http://wordpress.org/extend/plugins/blog-copier/