The ranger aa's flaming / frost arrows are currently working, but fairly useless. They cost 3/6/9 aa's, and they grant the buffs flames / frost of kesh'yk i-iii. they do -10 mana regen and add procs for 25/50/75 damage on bow attacks at a moderately low proc rate, in addition the flames has a dot for a couple tics of the same damage and the frost has a 1 second stun.
It seems to me that if the damage were improved it would be a good way to make up some of the dps rangers lose from panther type spells, and make ranged combat for rangers more comparable to melee combat.
At the current proc rates something on the order of 150/300/450 might be appropriate, considering you will get far more chances to proc in melee combat with double attack and 2 weapons.