HAppS is a great way to build web applications. Besides having a great feature set in its own right, it is probably the leading solution for implementing web apps in haskell, my favorite language.
If you use Ruby on Rails, Django, Perl Catalyst, PHP, or some other popular web framework, but have programmed in haskell and would like to use the world's greatest language for your next web project, just keep reading. I promise by the time you're done you will posess all the knowledge and sample code you need.
This tutorial is its own demo, and it is open source. The tutorial explains how to build a toy job board, which you can try out for yourself by creating a user on this demo site, and play with locally after you have installed the source code. The text you are reading this moment is bundled up too, hence "self-demoing tutorial." For best results, you should install and run it in a local environment where you have control. Then, when you are done learning, you can use the tutorial code as a starting point for your own HAppS applications.