PDFields is a project mainly written in C#, it's free.
A small application that shows you the editable fields in PDF Files.
A small .NET based application that displays a list of the editable fields inside of PDF files. I used this application as a way to test out pdf files that were created with editable fields for a small project at work.
You will need to use the itextsharp library in order to run this application. You can download the itextsharp library here: http://itextpdf.com. Once downloaded, you'll need to add a reference to the itextsharp.dll to your project.
Requirements: Visual Studio 2010 .NET Framework 4.0