Worked my neck mainly for football and some martial arts. If your into contact sports, always good insurance to work the total neck area, including the upper traps. Though doing trap exercises themselves does not always build up the neck.
Wrestlers bridges could be the best all around (360 degrees at times) movement. Heavy weighted neck strap or towel resistance from a training partner also works well. Some guy's even hook up a cable to a neck strap. One of the main functions of the neck is twisting from side to side, as well as front to back. So applied exercise accordingly. Go lightly at first, but the neck is a very strong short range muscle group.
A lot of BB's always seem to have a weak looking neck. In relation to the rest of their muscle mass, some do have pencil necks. Most always tell a athlete and a powerful man by his muscular (not fat, doubled chin types) necks and traps. Older people may benefit from neck exercise. Good Luck.