I had one.
My water broke before I felt any signs of labor. I'm not even sure exactly when it broke - I simply woke up that morning soaking wet.
Went to the hospital, labored for some hours with ineffective contractions. Walked up and down the hall probably hundreds of times, tried every position I could think of, nothing helped. After 10 hours or so of this my OB hooked me up to a pitocin drip. AGONY. Very soon I was having extremely intense contractions, one on top of another. Breathed, moaned, yelled through the pain, kept moving as much as I could with the IV in tow, kept trying different positions. Ended up sitting on DP's lap facing him for most of it, was barely even aware of who else was in the room at that point. Two hours of this and I was still only 3cm dilated. Got a shot of Stadol in my IV and it did nothing whatsoever.
Finally I broke down and asked for the epidural I'd been hoping to avoid. It turned everything around. My contractions were still so intense that I didn't feel the anesthesiologist inserting it at all. Within seconds I felt 100% better; shortly after that I dropped off to sleep. I don't know how long I slept, but when I woke up I was at 7cm. :Puke several times and that took me to 10cm, pushed for 20 minutes (I was pretty numb, but could still feel VERY strongly when I needed to push, and felt the baby crowning as well) and then I had a beautiful, perfect, 9 Apgar, very alert and eager to nurse little girl
If I hadn't had the epidural I really think I would have ended up with a C-section. It allowed me to relax enough for my labor to progress. My own mother labored for two days and never progressed past 6 cm, and I was born by C-section, so perhaps it's something genetic?