WYSIWYG toolbar in the editing window need not be as complex as the toolbars in the mock-ups at http://groups.diigo.com/Diigo_HQ/forum/topic/531
See suggestions at http://www.diigo.com/annotated/bd275badf20bce8bf709b39edb1a5cc9
The toolbar should include at least the hyper-link button/icon (to resolve angle bracket issues that cause loss of content), plus maybe the bulleted list button/icon.
Other features such as font, font size, underline and paragraph alignment are less useful (debatably undesirable) in comments and sticky notes.
Addition (upload) of graphics would be nice, if performance does not suffer.