Thanks for the fast responses. I guess we've never been handling this correctly, ever since 3e then. And here I thought I knew the rules pretty well.
We all knew you couldn't "provide flanking" to another character with a ranged weapon, but it appeared that you could reap the benefit of "getting flanking" from an attacker positioned on the opposite side. We read, re-read, and continued to hunt thru the rules to find anything contrary, but all the rules wording seemed to allow this line of thinking:
A) When attacking with a melee weapon, you give a flanking bonus to attackers on the opposite side of the target.
B) You can't give the flanking bonus using ranged weapon.
C) However, ranged attacks can reap the benefits of flanking if a flanker is on the opposite side fo the target. See A.
We'd essentially broken Flanking into 2 parts, a flanking giver and a flanking receiver. The giver needed to use a melee weapon and threaten the opponent, while the receiver was any character on the opposite side of that target. The receiver got the +2 attack bonus and it didn't matter what type of weapon they used. "Having flanking" simply meant there was a melee foe threating the opposite side.
I just checked the 3.5 SRD, and the wording seems a little more clear now than I remember it being, though I can see how I easily overlooked it with just a casual read. Maybe the rules haven't changed, but the wording got a clean-up along the way?
In any event, my gaming groups are in for a bit of a wake-up. I don't like using houserules if I can help it, so I'll try to implement this correctly in our next sessions.