Simple neck traction relieves pressure between the vertebras of the neck, gently stretches muscles and reduces headaches. This exercise has greatly helped my whiplash pain and migraines and it only takes 20-30 seconds. You don't need any traction device or fancy treatment facilities, it's as simple as taking hold of your head by the jawline and gently lifting to stretch and extend the neck. You can do it while lying down, sitting or standing. Don't twist or turn, just gently lift.
This video shows how you can use a towel or soft strap to do neck extensions at home: