Just a thought.
Bow strength is a very nice bonus feat for Rangers, that means Str is a must have stat for Rangers (unless they take Improved Weapon Finesse).
So Dex Rangers have a solution.
The problem is for Wis Rangers. It doesn't look like the DC things will work in epics.
So, I came up with this idea about a new feat (a free feat to lvl 8 Rangers):
Wise Bows
At lvl 8 can use (Wis-10)/4 bonus to damage for ranged attacks (if it's higher than Str mod bonus, or Dex mod bonus if you have Improved Weapon Finesse)
At lvl 13 can use (Wis-10)/3 bonus
At lvl 18 can use (Wis-10)/2 bonus (= Wis mod bonus)
Bonus to attack is still Dex (as in Bow Strength case). Also this feat doesn't grant proficiency with bows.
There could be also a new Ranger spell that adds +2 size bonus to Wisdom and damage (similar to Ram's Might).
This feat could be useful to other classes, like Clerics (actually I've seen a Clr playing with bow, I mean it was his main dmg).