Telerik RADEditor for SharePoint 2007 (MOSS)
I’ve been working with the Telerik RADEditor for SharePoint 2007 (MOSS) for a while now. It is a wonderful substitute for the out-of-the-box Rich Text Editor (RTE) that comes with SharePoint. It is highly configurable without writing any code, but if you want to get fancy, it is a well engineered ASP.NET application that is part of a suite of 18 tools.
If you’re at all frustrated by the native RTE (even if you are just looking for better cross-browser support), take a look at Telerik’s RADEditor.