When I started to build my website on Rails I didn't expect to find what I have found today. It is Active Admin and CKEditor gems which turned out to be extremely convenient and easy to customize. With them I already have the biggest part of my blog functionality ready. And what is also very nice is that Active Admin works with Devise almost out of the box.
And maybe even more important is that Active Admin would be a great gem to use in any real project, like online shopping app for instance.