This product adds a whole new level of flexiblity to d20 Modern. I really enjoy talent trees and always looking for new ones to add to my game.
Some of the talent trees I thought to be espically useful are: Strong Heroes - Like a Rock (adds a natural armour bonus).
Fast Heroes - Elusive (adds a dodge bonus and makes it harder to hold the character down) & Need for Speed (special tricks to make your character an amazing driver)
Smart - Fast Learner (additional skill points, higher max skill ratings)
Dedicated - Animal Friendship (bonuses to interact with animals and at higher levels the ability to summon animals)
Charismatic - Facetious (Talents that make the character espically good at humour)
Unfortunately the Tough Hero only has 2 talent trees, FX Resistance and Poison Resistance. Although the Like a Rock talent may be a good choice to add to the Tough's talent list.