For all the fashionistas that want to know why fashion exists, which are it's mechanisms and the impact of the fashion phenomena on every day life, here is a book written by Georg Simmel in 1911, the first sociologist that covered this field coming up with some theories that are still available today.
It was my starting book for my university graduating essay, being a very important sociology book.
You can find on amazon.com (http://www.amazon.com/Simmel-Culture-Selected-Published-association/dp/0803986521/ref=sr_1_1?ie=UTF8&s=books&qid=1256290977&sr=8-1) a selection of his texts. Unfortunately I didn't find an englush version available on the internet.
Here's picture of the cover and also the only picture that I found on the romanian version.