GeoExt
  GeoExt is a JavaScript library that provides groundwork for creating rich web mapping applications. It combines the web mapping library OpenLayers with Ext JS - a cross-browser JavaScript library for building rich internet applications. GeoExt provides a suite of customizable widgets and data handling support that makes it easy to build applications for viewing, editing, and styling geospatial data.
Features
- Built with Ext JS, cross-browser rich Internet application framework.
 - Integrated OpenLayers mapping client.
 - Full dynamic user interactivity and animation without the need for Flash or Silverlight.
 - Well designed and extensible component model.
 - Wide variety of generic widgets (grids, charts, trees, layouts, combo boxes, toolbars).
 - Flexible, standards-based mapping widgets like legends, pop-ups, and scale choosers.
 - Printing controls from PDF serving platform, such as page layouts, resolution, and legends.
 - Customizable layer selection.
 
More about GeoExt:
    http://www.geoext.org/