Client Administer

I’m currently researching MiddleMan for use in a upcoming project. One part I am unsure of is, how would a client manage/edit the content? Is there an extension or solution for providing the client an easy interface for basic editing of the content?

it doesn’t really. You can store the content in a git repo and have your client edit the content from that repo, but it sounds like you are probably looking for a full blown CMS where they can edit content in a WYSIWYG editor.