I recently switched to MongoDB and I am wondering if I can continue using any of the popular admin interface solutions, such as ActiveScaffold and Typus?
ActiveAdmin https://github.com/gregbell/active_admin is a great tool for the admin interface creation. And I believe sooner or later they add mongoid support.
Right now there's some patch for it: https://github.com/ebeigarts/mongoid_active_admin_app I didn't try it myself though.