Мне нравится и я использовал tinymce редактор, это пример кода, похожий на следующий.
<script src="/javascripts/tiny_mce/tiny_mce.js" type="text/javascript"></script>
<script language="javascript" type="text/javascript">
tinyMCE.init({
mode : "textareas",
theme : "advanced",
plugins : "safari",
convert_urls : false,
width : "560",
height : "15",
// 'code' in 'theme_advanced_buttons1' is used for the HTML content
theme_advanced_buttons1 : "fontselect,fontsizeselect, separator, bold,italic,underline,separator,forecolor,backcolor,code, justifyleft,justifycenter,justifyright,justifyfull",
theme_advanced_buttons2 : "",
theme_advanced_buttons3 : "",
theme_advanced_toolbar_location : "top",
theme_advanced_toolbar_align : "left", extended_valid_elements : "a[name|href|target|title|onclick],img[class|src| border=0|alt|title|hspace|vspace|width|height|align|onmouseover|onmouseout|name], hr[class|width|size|noshade],font[face|size|color|style],span[class|align|style]" });
</script>
<textarea cols="40" id="template_content" name="template[content]" rows="20"></textarea>