Here's a selection of US companies that sell women's shoes in extra large sizes (and suitable for tall women). Most of them have a selection of shoes in up to at least US size 12. I'm always adding new stores to the list.
For the best choice of shoes in large sizes check out Long Tall Sally (up to US size 15), Zappos.com (up to US size 16), Shoeline (up to US size 13), Shoebuy (up to US size 17) or ShoeMetro (up to US size 14 1/2). They are all US companies but they ship internationally. Amazon.com also sell women's shoes in up to US size 16.