This plugin by Keith Graham allows all blogs on a network to use the options set on the Main Blog (blog #1).
The WordPress administrator can check off which options are to be shared among blogs. Almost all the current options are listed by name. Once the options have been checked and the plugin updated then all other blogs will see the option value set in the main blog.
This is useful for networked blogs where some options do not change across the blogs.
The primary reason for this plugin is to let all blogs use the same WordPress API key, so that Akismet does not have to be configured on each blog, and it is not necessary to hack WordPress files to share Akismet.
The author says ” I consider this plugin to be potentially dangerous for the casual user. If you get in trouble uninstall the plugin from the main blog or delete the plugin from the plugins directory.”
Download and more info : http://wordpress.org/extend/plugins/mu-global-options-plugin/