There have been a few times that I've put this skill to use. In my experience, being able to play the guitar and sing (albeit only decently) is quite the asset. Last Spring I was dating Mandy for about three months. It was probably around month two that I gained the confidence and desire to play a song for her. I chose to sing her California Stars.
I'm not sure what it is about that song but it scored major points. I love the lyrics and enjoy playing the song too. It isn't too difficult to play, so I'm able to be a little goofy and act overly emotional during it.
Then there has been one other girlfriend that I've played a song for on a couple occassions. What I'm thinking of is when I played a song for Heidi that I wrote. Somehow it was enough to bring her to tears. At one point I had the lyrics and chords written down, but I've since misplaced them. I remember the chorus:
Some days I actually forget
That this is really something
One smile from you and that is it
This is really something
Being hard is hard so sick of it
This is really something good
This is really something good now
I wasn't really happy with the lyrics that I wrote for her, but she loved it. There have only been a couple times a girl has cried tears of happiness due to me, and that was one of them.
Tonight, after reading some constitutional criminal procedure I grabbed my guitar and started to play a few songs. I called my friend in New Mexico and played her a newer song by Fountains of Wayne which made her laugh. I just need to get a little more comfortable with playing for people, because it does seem to bring happiness if you have even a minor amount of talent.