Has Your String Got A Hang Up

Here is a useful bit of knowledge that comes in very handy when a guitar string hangs up in the slot.Sometimes the slot(s)in your nut are not cut good,or rounded at the bottom.This will cause the string to get pinched or caught,causing it to go out of tune.We are talking about a standard nut here,no lock downs.
I use a pencil and rub the tip across the slot then put the string back in the slot,this basically lubricates the slot with graphite from the pencil tip.Another way is mixing graphite and vaseline together and with a toothpick,dab it into the slots.And another way i just heard about was using lip balm!I will have to try this out.And,if you do let me know...
And check an article about the different types of nuts and the tones they have...
http://guitarplayer.wordpress.com/2009/02/02/guitar-tone-tips-nuts/