Does anyone have a list of what constitutes an "extrodinary quality that improves ranged or melee attacks"?
I get that the ability has to have (Ex) but is that sufficient? I assume things like pounce and grab would be ok, but what about things like poison?
It seems I've been able to partly answer my own question. Everything which is listed in the glossary is actually a special attack (which is a little odd since the descriptions of such things are listed under the "special abilities" section of stat block. In order for something to qualify as a special quality (rather than an attack) it must be listed in the SQ section of the stat block at the end of the statistics section. Furthermore, undead like skeletons only keep the ones which improve their ranged or melee attacks.
Off the top of my head, I can't think of anything which qualifies.
It seems there are very, very few which qualify:
Undersized Weapons
Oversized Weapons
Powerful Bite (Tyrannosaurus is the only one?)
Magical Strike (Unicorn and Half-Celestials)
Tenacious Grapple (though grab and constrict are lost)
Multiweapon Mastery
and possibly a couple more I've missed.