I'll add those things that have helped my plantar fasciitis:
a soft rubber roller. Sit in a chair and roll your arch back and forth. It seems to help. Only problem? My dog thinks it's a toy and keeps stealing it
http://www.roadrunnersports.com/rrs/products/FOL001/
MBT shoes (for the street, not the dojo). When I first put them on, I didn't have some instant sense of how great they were, but after just a few days, my feet stopped hurting. Goofy looking, expensive (but check the internet and save some money), but these really help. Recommended to me by several other long time MA. I don't know if the similar looking Sketchers work as well.
http://us.mbt.com/
lots of sites selling these appear to be bogus. Stick to Amazon or legitimate stores.
tape your foot before class. this is the way I do it (heel to toes). Lots of variations
http://www.youtube.com/watch?v=fuoFjr9xPBc&feature=player_embedded
Stop doing jump kicks/stomp kicks etc for a time. This may have helped me the most. (I train on wood floors, not mats)
Physical therapy: There are exercises that will strengthen the foot. Go a couple of times and then just do the exercises yourself.
Some doctors will suggest a direct injection (of steroids) into the foot to reduce the selling and pain. Be careful of this. The steroids can soften the ligaments and set you up for a later injury. Short term relief but long term danger.
Custom orthonics: I tried this. They made a mold of my foot and made a custom shoe liner (for when I run). Expensive, the liner broke down quickly, and I didn't sense a big improvement. Maybe a rip-off.
Plastic heel cups that slide into the shoe. I use them. I can't tell if they really help, but they were cheap and the MD recommended them.
FWIW, my primary doctor recomemended against the surgery (for both heel spur and PF). She said they sometimes will not heal correctly and you might create a recurring pronblem. She sent me to a podiatrist with the same opinion.
There's a wholes series of air-boots, ankle/arch supports, etc, that a doctor will give you. If you choose to see a doctor, go to one who understands runners and athletes. Too many (who don't get athletes) will tell you to stop doing anything that aggravates your feet. You want someone who will help you keep training, not someone who thinks walking the dog up and down the block is exercise.
One of my students had bad PF. I got him a pair of mid-range Adidas karate shoes. He swears by them.