Feb 2019 Update - I have moved the Handlebar Code into it’s own project and its available as a stand alone module without needing to worry about Sitecore Foundation. You can find the code and installable Sitecore Packages on github here.
Tools like WFFM make it easy for content authors to build simple forms, but it is sometimes challenging to get those forms to match the design provided by an agency, and is sometimes difficult to leverge when you want to use your favorite JS or CSS library.
At the same time, it feels heavy to create a new component for every form that you need, even though that gives you the most control over both the display and processing of that data.
With all this in mind, I thought this would be a useful area to expand our library of Handlebar components to support. If you're not familiar with them, these components allow you to define custom Handlebar templates that are stored in Sitecore and allow you to bind to other content items also in Sitecore. They can bind to single items, collections of items and even the results of Content Search Queries.
Handlebar Forms take this a step futher and allow you to define the form markup completley in a handlbar template, binding to a content item for form labels and thank you messaging. In addition, it provides an interface for building form processors which can handle the data. So if you have specific logic in mind, you can define your own processor. Or you can use one of the two I've already created. One allows you to map form parameters to SQL command parameters to insert records into a Database table. The other leverages another new feature of Sitecore Foundation: User Settings, which allow you to store data in xDB in a custom facet for storing user specific key value pairs (more on this in the future).
It's a lightweight but powerful way to quickly create forms and handle submitted data. Here's a video overview of the current implementation.