I can't remember the poster who first posted this (I want to say Col Hardisson?), but one poster last year commented that in their opinion Intimidate is looked at incorrectly. Intimidate is the skill at communicating that you are fully capable of carrying out what you say you will do. In other words, if someone is not afraid to enter combat with you, or has no reason not to, intimidate is useless. Otherwise, heroes could just intimidate their way through entire dungeons full of humanoid nasties who spoke their language. It's not the skill of getting someone to do what you want, but that they face the worst you have to offer should they NOT do what you want.
Will intimidate from a Halfling commoner work on a hill giant? It depends on what he threatens. If the halfling commoner with 18 CHA, 4 ranks and skill focus in initimidate threatens, "do what I want or I'll smash your face in," then unless that halfling also has a high strength, then chances are the hill giant will shrug it off - after all, what's the worst the runt could do?
On the other hand, if said halfling says, "It'd be a shame if your wife Mrs. Giant found out you were hiding gold from her - and I know just where she can look if she wants proof," then even IF said Hill Giant wasn't doing anything shady, would Mr.s Hill Giant beleive him anyway?

The threat says, "I've got something on you, or I can make someone else believe I do," then that's intimidation on a threat that the shrimp can REALLY carry out.
Intimidation is belittled severly if all you use it for is threat of physical violence. However, cunning PC's with no combat training can use this skill to effectively blackmail anyone, even the staunchest Good Paladin.
Just another way of looking at it.