Although the TinyMCE editor currently being used by Hudu is awesome, there are certain functions (or lack thereof) that introduce some frustration when creating documents. One such function that is lacking is the ability to continue numbering a numbered list if say you need to insert a callout or horizontal line in between the numbered steps. The moment one of these are inserted, the numbered list re-starts at "1".
Another function: paragraph line spacing options (e.g. 1x, 1.15x, 1.5x, etc.) to introduce more spacing between lines, making reading easier.
I would say that these two are top functions that would make the TinyMCE editor absolutely great.