Unless your name is Jeff Willett, you really don't need to train the neck on a regular basis.
It's kinda fun to train it for a few weeks every now and then though IMO.
Use wrestling bridges.
A few tips:
Start off from your knees, and support with your hand on the ground, preferably some kind of padded mat.
Roll on your forehead left and right, move the weight. And back and forth as well.
Then turn around. The first couple of times, lay with your ass on the ground, and lift your upper body up with your head, while supporting with the hands.
After a few weeks you will be up in a real bridge.
Key is to increase the load progressively, then you'll avoid injuries and also build a stronger and bigger neck.
I like the excersise mainly because it helps me avoid injuries, helps the general condition.
YIP
Zack