Jennifer Kolari's blog post has certainly hit a nerve among parents. I've heard from quite a few people dealing with this very thing. Further to Jennifer's suggestion to give the anxiety a name, my own therapist has suggested to me that I also give it a face. This is cognitive behavioral therapy and should work for your own anxiety or your child's - it certainly helped me.
I was told to come up with an image of what my anxiety looked like - short or tall, what color, etc. What I came up with was a tangle of purplish-brown hairy lines with cartoon eyes, hands, and feet. Right away, my own creature was sort of cute in an annoying way. He only came up to my knees, so I was the one in power. But the greatest thing about creating a separate persona for my fear was that it then existed outside of me--no longer within. It wasn't a part of me, it was a little being I could order away from me if need be.
For example, if I was going to a reading and was nervous, I could imagine this hairy beast, tell him he was not allowed to follow me (bookstores tend to frown upon purple hairballs hanging around, don't they?). My therapist said to give him (see - already he has a gender, ha!) one spot in the house where he was allowed to exist and banish him to his spot when you want to get rid of him.
So if your child is experiencing anxiety, ask her what her anxiety looks like - if it could look like anything in the world. Let her create this creature in great detail and laugh over little parts of it--the ragged ears or yellow teeth. Then have her name it, decide how large or small it is. Let her discuss it's odd habits, then pick the spot where it's allowed to live. Your child will have so much more power over her anxiety, you should see an improvement right away. And as she banishes her little creature to its spot more and more, the creature's strength will gradually begin to fade, leaving your child free from its ugly cracked toenails more and more.
I'd love to hear if it works for anyone - even if you try it for yourself!