There are currently 4 admin interfaces to the Midgard Content Management Framework, and together with the Framework they provide a complete CMS. By default only two of the interfaces are installed with the Midgard packages, Old Admin and Asgard. Due to licensing issues Aegir has to be installed separately although this is quite easy. There is also Spider Admin, a newer version of Old Admin that has had a code cleanup and support for sitegroups added and the choice of htmlarea version 2 or Ekit (a java based WYSIWYG editor) for text areas. They are all somewhat different and you might prefer to just use one or switch between them depending on the task that you are undertaking.

There is also MidCom, the Midgard Component Framework which has just been released but may well offer an alternative and very customisable admin interface.