Is there a Firefox/Mozilla control for embedding the firefox browser in a C# .net application?
Even better, there is a fork by hindlemail, actively updated DLL for .Net, here: https://bitbucket.org/geckofx/. Currently, there are available versions corresponding to Firefox's version 10 and 11.
You can have the Gecko rendering engine in the form of GeckoFX.
To quote Google Code:
GeckoFX is a Windows Forms control written in clean, commented C# that embeds the Mozilla Gecko browser control in any Windows Forms Application. It also contains a simple class model providing access to the HTML and CSS DOM.