Plantar fasciitis is what used to be called "fallen arches" back in the olden days. The plantar fascia runs from near your toes (the ball of your foot) along the arch, under the heel (where it becomes your Achillles Tendon) and up the back of your calf.
Had a case of it a few years back that actually put me in a soft cast.
You need shoes with a really high arch. Some folks have mentioned Birkenstocks. They are good. Certain pairs of crocs are good as well, but you really have to take a good look at the arch. The "Modi" style of Crocs flip flops has a pretty good arch. I have been wearing them for a while now without difficulty.
As far as treating it...I have done the "rolling the frozen water bottle" thing. Notbad, but I have more luck with rolling a golf ball under my foot. HUrts when you are rolling it along the arch. Hurts like HECK when you get it on the bottom of the heel but after a few minutes you will suddenly feel warmth and relief from the pain...it's kind of amazing. But you do have to suck it up through some fairly significant pain for a few minutes.
The best stretch I have found is the cross country skiing stretch...that is what my podiatrist calls it. It is best done without shoes on. You get your legs in line with the width of your shoulders and point your toes in at about a 30 degree angle. You then bend at the knees, as if you were skiiing. You hold this position for 10-20 seconds....as long as you can stand it. Then straighten your legs and rest for the same amount of time you held the position. Then bend your knees and repeat it. Repeat it for 20 repetitions. If you are doing the stretch correctly you will feel the stretch/burn along your calf and down into the back of your ankle (Achilles area).
I do these several times daily. I do them when I am standing in line at WDW. I do them if I am talking on the phone at work or at home. I just do them constantly to keep that ligament/tendon/fascia stretched.
