Currently I am following the Developing Data Products class from Coursera. The class is part of the Data Science track that I am following since last year. The goal of the class is to learn about how to create products from the work you have done. This can be a presentation, an R package or a web application for example.
The course project of the class consists of creating a shiny app and a slidify presentation.
Shiny also has a lot of control widgets (e.g. buttons, sliders) where a user can interact with the application.
Slidify is a tool that can be used to develop presentations that are written in RMarkdown. You can embed R code in the Markdown language and the presentation is compiled from this source. Handy if you just want to change some code lines or data input without wanting to create a new presentation.
Slidify has a nice integration with Github, Dropbox and RPubs: it can be uploaded via the publish command in the slidify package.
For my course project, I have chose to create an app and a presentation of the old faithful dataset, simply because I like geysers:-)