Hi Stuart,
I think ligature use is determined more by the type of font in question. I've been working on an antique style handwriting font lately. In handwriting, forms are predominantly connected. Most connections can occur smoothly in the same place. I find that letters whose stroke end at the top such as o v w and sometimes b often work best with ligatures. w_h is one that seems to flow better that way. I don't always make ligatures for double letters as contextual substitution seems to cover that well enough. Exceptions to that are usually combos with crossbars like f_t t_t or things like oo. Sometimes I get tempted into spicing things up a bit and include ligatures that are for beginnings only.
All this is assuming we're talking about Open Type ligatures as opposed to creating a 2nd PS version with extras. If you go too wild with ligatures you have to watch out for conflicts. For instance, if you have both o_o and o_n you might consider an o_o_n ligature to be first in line.
Hope that helps ...not exactly a list.
Stephen







