Sitting on my bookshelf waiting to be read is The Millionaire Woman Next Door. Which probably has the answer to your question, but I don’t know it yet…
My field, HR, is women dominated (about 75% women). However, it is not women dominated at the top. I recently saw a list of the top 10 highest paid HR executives–not a woman in the bunch. I feel I make a decent living. It is similar to finance in terms of potential, I think.
For highly paid fields where women do well, I would agree with those who mentioned real estate. I have also heard that women at the top of Mary Kay and Avon type businesses do quite well.