This plugin by David Cartwright brings site-wide-like administration options to the frontend, allowing group admins simpler management of all of their groups.
It can be further extended using the standard buddypress profile subnav registration functions (for example, the bp-wiki plugin hooks into this to enable movement of wiki pages between groups).
Currently only recommended for use with the bp-wiki plugin. I will be extending this shortly to provide some more general multi-group controls and documentation for extension.
Plugin homepage: http://namoo.co.uk/