Docking control - JaStDev's Docking control is a component library for WPF that helps you build complex Tabbed document interfaces.
Zee ASP.NET Docking Control - First ASP.NET server control that creates Visual Studio style docking panels. Can auto-hide/slide-open/maximize/pin tabbed-panels. Appearance customizable via CSS & Themes. Works with MS ASP.NET AJAX. Supports all major browsers, quirks/strict modes.