Well, they seem to be able to spread the "curse of therianthropy" to frost giants, so that's probably one. I kind of like the rage option from ToH for these, too.
Tome of Horrors said:Battle Frenzy (Ex): This special attack functions only when the therianthrope is in animal or hybrid form. It does not stack with any other rage or battle frenzy ability the base animal may possess. Once per day, the therianthrope can work itself into a battle frenzy similar to the barbarian’s rage (+4 Str, +4 Con, +2 morale bonus on Will saves, -2 AC penalty). The frenzy lasts for a number of rounds equal to the therianthrope’s HD, and the therianthrope suffers no ill effects afterwards.
Tome of Horrors said:Fear (Su): This special attack functions only when the therianthrope is in animal or hybrid form. The therianthrope can, by making a loud sound appropriate to its natural animal form (roaring, barking, braying, or the like), unleash a frightening blast of sound. All creatures within 30 feet that hear it must succeed on a Will save or become panicked for 2d4 rounds. Creatures further away but within 200 feet must succeed on a Will save or become frightened for 2d4 rounds. This is a sonic, mind-affecting fear effect. A creature that successfully saves cannot be affected again by the same therianthrope’s fear for one day. A therianthrope is immune to its own fear effect and the fear effect of other therianthropes of the same base animal type.
Tome of Horrors said:Summon Animals (Sp): Once per day, the therianthrope can summon a number of animals of its same type whose total Hit Dice do not exceed twice its Hit Dice (for example, a 3 HD wolfwere could summon 6 HD worth of wolves or 1 dire wolf once per day).