We've been going through a massive reorganization of our house this summer and it's caused me to rethink my wardrobe.  I would love for it to be more versatile.  So far I've read...

Shop your closet: the ultimate guide to organizing your closet with style by Melanie Charlton Fascitelli with Kevin Clark — The book that started the geek out.  I was looking for books on organizing closet space and ended up with this one that also devotes chapters to cleaning out your closet, packing a suitcase and shopping

The one hundred: a guide to the pieces every stylish woman must own by Nina Garcia ; illustrations by Ruben Toledo — This book is interesting but some of the things considered "essentials" are really silly...Missoni stripes a neccessity?  Maybe not so much

What I Wore by Jessica Quirk.   I love her blog and she gives lots of good ideas for building outfits
according to season. I had to interlibrary loan it.

The No-Brainer Wardrobe by Hayley Morgan. An eBook I bought off her website for $8.  Hayley gives a historical background to the clothing market, and explains how to build a wardrobe that can be changed around to build multiple outfits.  She also gives tips on shopping at Second Hand Stores or Trendy low price stores like Old Navy or Target.  I put it on my Kindle and I won't be deleting it!