elRTE is a comprehensive, free rich text editor for the Web
Formatting text for the Web is an ongoing quest. HTML has a fairly steep learning curve, but people still need to blog, comment, and somehow format text.
Personally, I'm a huge Markdown fan. In my opinion, if you're trying to write a blog post with formatting that can't be expressed in Markdown you're putting too much emphasis on the formatting.
Still, not everyone likes Markdown, and sometimes circumstances call for a rich, visual content editing control. There are a ton of such controls floating around (with CKEditor being the best-known one), but elRTE seems like a worthy contender.
One of the things I like about it is that you get a bottom bar that shows you exactly where you are in the document hierarchy (i.e., "div > table > tbody > tr > td"). Also, all of the dialogs (for adding tables, images, etc.) are comprehensive, and each provides a ton of options.
Again, I don't think it's a control that I would personally use, because it's huge (some might even say "bloated"). But if some of your users require a visual editor, while others require fine-grained control over the HTML that they create, elRTE might provide a reasonable compromise.