A while ago I asked for Rich Text Editor recommendations, and Ferdy pointed me towards TinyMCE.
The project I needed an editor for was a low priority one, and I ran out of free time, so it was only recently I got around to taking a look at TinyMCE. When I did, I felt kinda silly, because it only took 5 minutes to download, skim the .NET example, and fully integrate it into my application. Neat.
Out of the (free!) box, it offers a lot of good stuff, it's easy to customise, and basically does everything I need it to.
However when I went to deploy it to my web host, all I saw was the yellow screen of doom. My hosting provider has retail deployment turned on, so I don't ever see meaningful errors, however had a feeling it was TinyMCE causing the problem, which it was, relating to trust levels: "Failed to grant minimum permission requests".
Fortunately, there's a pretty easy fix for this, assuming you have Visual Studio installed. Simply download the TinyMCE .NET package which includes the source, open it, build it, and use the output DLL instead of the prepackaged one. Alternatively, you could add the TinyMCE project to your application solution. Done.