I just updated admin_view to work with Rails 4. It's a small code generator that can create a nice Bootstrap-friendly admin interface for existing Rails models. I find this useful because admin interfaces I work with almost always need to be customized, and this gets me to that point quickly. More background here.
admin_view is new kid on the Rails admin interface block. It generates a small chunk of opinionated scaffold-like code with a simple search form on a paginated, column-sortable listing. Read more on the announcement blog post.