Draper adds an object-oriented layer of presentation logic to your Rails application. Without Draper, this functionality might have been tangled up in procedural helpers or adding bulk to your models. With Draper decorators, you can wrap your models with presentation-related logic to organise - and test - this layer of your app much more effectively.
Paranoia is a gem that allows you to hide records instead of destroying them. You can recover them later if you want. It’s a very simple (one file with about 300 lines of code) reimplementation of ActsAsParanoid.
Cloudinary is the image back-end for web and mobile developers. In other words, it allows you to upload images to the cloud (let's say it's something similar to S3), but in addition it allows you to do many different image (and video!) transformations on the fly, just by changing URL params.