The industry preferred Telerik rich text Editor for ASP.NET AJAX comes with a custom wrapper that can be immediately plugged in any SharePoint 2010 project. The benefits of our editor are: clean XHTML output, tons of available features and customizations, fast rendering, and wide cross-browser support. The editor can be activated in different scenarios across some or all web sites in your SharePoint farm. You can also leverage the RadEditor control for custom web parts or other SharePoint solutions development.
Click here to see a demo of the RadEditor for SharePoint 2010
The editor easily integrates into existing SharePoint sites. After one or both of the editor features are enabled from the site features page
It can replace the original editor in lists:
...and in page fields on the site: