Ask For It: How Women Can Use the Power of Negotiation to Get What They Really Want by Babcock, Linda, Laschever, Sara [Bantam, 2009] (Paperback) [Paperback]
Self help style books just never do it for me - I wanted more incisive looks at failed negotiations and analysis about why they failed. Also there was a real white feminist vibe to this whole book (product of its time).