I would recommend a couple of different courses, actually.
Go to a doctor and have it checked out. There are two different types of snapping hip syndromes, and each have different causes and recommendations. You could be trying the cure for one, when it is the other one that is causing it.
Check your shoes and have a gait analysis done.
I had snapping hip in college cross-country caused by uneven wear in my shoes that I didn't switch out properly, and ran too many miles on worn out cushioning. Often you can't tell from a visual inspection that your cushioning has lost its effectiveness, you have to pay attention to how your body feels. When you start feeling more "beat up" or have other small aches/pains, it may be time to change shoes. Also, be cautious of wildly varying mileages from week to week. If you jump from 10 miles to 50 miles to 30 miles and back to 45, it's easy to create injuries where there shouldn't be any.
Ibuprofen, ice baths (although I don't recommend these unless prescribed, easy to do cold damage to personal parts), stretching and massage can all help alleviate symptoms, but unless you address the root cause, it will just come back.
Another method you can try is Active Release Therapy (ART), and foam rolling the area. You can either try this on your own or find an ART therapist locally to show you how at first.