Plantar Fasciitis inserts
As someone who has been in shoe service for 15 years and had plantar fasciitis 3 times in my life, I've found some seemingly counter intuitive things to look for in an arch support.
The first thing is you obviously need it to be strong, with a pronounched arch. Not so counter intuitive, but this is the starting point when looking for Platnar fasciitis inserts.
The second thing is you want to make sure the insole is rigid. Being able to bend the arch in half means its not going to do jack squat for your feet.
Finally, and this is one of the counter intuitive things. Avoid excessive cushion like the plague. I was rather suprised to figure it out. highly cushioned insoles barely do anything for your feet when you have plantar fasciitis.
If you want some examples of great inserts for Plantar Fasciitis, check out http://orthoticsplantarfasciitis.com/. They showcase insoles that help with plantar fasciitis and generally support your feet to keep them happy. :)