I'm working on Yet Another CMS in my almost non-existing sparetime. A CMS needs a WYSIWYG editor, and anything that can save me time is a ++.
I tried FCKeditor, a really nice and very popular editor. But TinyMCE seems just much easier to set up.
It really is a matter of getting, unpacking and adding a couple of lines in the wrapper page:
<script language="javascript" type="text/javascript" src="../js/tiny_mce.js"></script>
<script language="javascript" type="text/javascript">
tinyMCE.init({
mode : "textareas"
});
</script>
TinyMCE is at http://tinymce.moxiecode.com