They are good on mounted companions with a little 'horse archery,' because they only use up one slot, and when they run out (quickly) it forces the companion back into melee as they switch back to either their lance or short range weapon.
So I guess I use throwing weapons as a way to fool the A.I. into backing off for another charge after the initial impact... and a way of forcing the A.I. companions out of the bigger early melee mobs.
If you're investing highly in ranged weapons (7-10 power draw) - bows are pretty much it. But around 3-6 power throw, throwing weapons do significantly more damage than any other ranged options. There is the issue of accuracy and ammo, though, which makes them ideal as a weapon to toss just before engaging in a big melee pit. If you're just tossing them into the crowd, you can't go wrong. When you play on foot, and with Nord infantry, it's easy to pick up all of the thrown weapons too.
Though a bow might be a better choice for a more dedicated ranged cavalry unit, I am a big fan of equipping myself with a light lance, shield, long arming sword, and jarids in order to use the jarids to take out fleeing enemy cavalry, or to assassinate strong units early on. Jarids simply deal massive piercing damage, and you get to keep your shield up to stop any ranged fire you might take while going for the early strike on enemy priority targets.
There's also something to be said for the 'balanced heavy throwing axe,' because when you use one in melee, it's one of the best 'melee pit' weapons out there. It's very fast, it gets a bonus against shields (though it isn't listed), it has a short range which allows you to side-swing even in cramped situations like sieges, and it deals a good amount of damage. Perfect for swapping between throwing and meleeing for a turtle-exchange of hits.