List of components

- Freetextbox (up to SP v. 2.1)
Website: http://freetextbox.com/default.aspx

FreeTextBox is the most-used HTML editor for ASP.NET. It is compatible with IE on the PC, and Mozilla and Firefox on all platforms.

- CKEditor (since SP v. 2.2)
Website: http://www.ckeditor.com/

- Webchart (up to SP 2.3) 
Website: http://www.carlosag.net/tools/webchart/

WebControl for creating charts, that render as images(png, jpg, gif, etc). Supports:
Line Charts, Smooth Line Charts, Column Charts, Area Charts, Scattered Charts, Stacked Column Charts, Pie Charts, Stacked Area Charts. Featuring VS.NET Designer support and more.

- Microsoft Application Blocks for .Net (up to SP v. 2.1.)
Website: click here

http://support.microsoft.com/kb/829028
The Data Access Application Block is a Microsoft .NET Framework component that contains optimized data access code that can help you do the following:

- Call stored procedures.
- Issue SQL text commands against a SQL Server database.

The Data Access Application Block returns the SqlDataReader object, the DataSet object, and the XmlReader object. You can use the Data Access Application Block as a building block in your own .NET Framework-based application to reduce the quantity of custom code that you must create, test, and maintain.

- Microsoft Enterprise Library DAAB (since SP v. 2.2)
Website:  http://msdn.microsoft.com/en-us/library/dn169621.aspx

- ASTreeView component
Website: http://www.astreeview.com

ASTreeView is a full functional treeview control for ASP.NET with drag drop, Ajax loading, context menu, XML import/export, checkbox, selection, adding/editing/deleting nodes with Ajax.