I am permanently banning "There Goes My Life" by Kenny Chesney and "Don't Take The Girl" by Tim McGraw from my at-work listening material because I ball every time I listen to them. Something about being a daddy and having a little girl makes those songs stick in my throat.
Ed. Update: Strike that. Just about any country has that effect apparently. Must be my time of the month.

I have that problem with the John Michael Montgomery song, "Letters from Home." It reminds me of Adam and I have to change the station when I hear it on the radio.
My Dear Son, it is almost June,
I hope this letter catches up to you, and finds you well.
Its been dry but they’re calling for rain,
And everything's the same ol’ same in Johnsonville.
Your stubborn 'ol Daddy ain’t said too much,
But I’m sure you know he sends his love,
And she goes on,
In a letter from home.
I hold it up and show my buddies,
Like we ain’t scared and our boots ain’t muddy, and they all laugh,
Like there’s something funny bout’ the way I talk,
When I say: "Mama sends her best y’all."
I fold it up an' put it in my shirt,
Pick up my gun an' get back to work.
An' it keeps me driving me on,
Waiting on letters from home.
My Dearest Love, its almost dawn.
I’ve been lying here all night long wondering where you might be.
I saw your Mama and I showed her the ring.
Man on the television said something so I couldn’t sleep.
But I’ll be all right, I’m just missing you.
An' this is me kissing you:
XX’s and OO’s,
In a letter from home.
I hold it up and show my buddies,
Like we ain’t scared and our boots ain’t muddy, and they all laugh,
'Cause she calls me "Honey", but they take it hard,
'Cause I don’t read the good parts.
I fold it up an' put it in my shirt,
Pick up my gun an' get back to work.
An' it keeps me driving me on,
Waiting on letters from home.
Dear Son, I know I ain’t written,
But sittin' here tonight, alone in the kitchen, it occurs to me,
I might not have said, so I’ll say it now:
Son, you make me proud.
I hold it up and show my buddies,
Like we ain’t scared and our boots ain’t muddy, but no one laughs,
'Cause there ain’t nothing funny when a soldier cries.
An' I just wipe me eyes.
I fold it up an' put it in my shirt,
Pick up my gun an' get back to work.
An' it keeps me driving me on,
Waiting on letters from home.
Yeah, I agree with Laura. I myself have narrowly missed a few "opportunities" to head to the land of sand, but that song really hits home, especially with me having so many of my Air Force buddies over in Iraq. With me not having children and all, I guess it's hard for me to relate to the kids thing, but JMM is right, when you're in the military and isolated and away from everyone you know, a letter from home is the best thing that can possibly happen. And that was just basic training, I'm sure combat is 100x worse.
If you want a country song to really give you the chills, try "Midnight in Montgomery" by Alan Jackson. Awesome song.