1)   Elegant Ribbon 2
Elegant Ribbon is a set of Windows Forms controls that allow you quickly and easily provide your application with a new-generation user interface like that introduced in Microsoft Office 2007. It is written in 100% managed C# and is CLS compliant.

 2)   PureComponents Ultimate Suite for .NET 2008.1
PureComponents Ultimate Suite is a set of 79 controls for .NET WinForms. It contains all controls you need for developing the user interface. You can find there controls for displaying data in a grid, calendars, controls for creating forms and more.

 3)   SharpWidgetsUI 1
SharpWidgetsUI offers a set of lightweight Windows Forms components including Office 2007 ribbon and look and feel. SharpWidgetsUI is built on top of an innovative component infrastructure, which results in high performance for your applications.