Hi Chainsaw,
I'm not a natural lyric writer so these are the books that have helped me recently:
Stolpe, Andrea: "Popular Lyric Writing, 10 steps to Effective Storytelling", (Boston, Berklee Press, 2007)
This really helped me to start balancing different types of imagery and to look at balancing odd an even patterns, and also hook placement, and key word placement.
Blume, Jason: "Six Steps to Songwriting Success: The Comprehensive Guide to Writing and Marketing Hit Songs" (2008) cant remember publisher
This one is ok, gave me a REALLY useful technique called the 'lyric palette'
Davis, Sheila: "The Songwriters Idea Book", (Ohio, Writer's Digest Books, 1992)
This one is great, a sourcebook, with tons of ideas in it. I use it to dip into just to spark ideas off, (when I can prise it out of my students hands!)
There are others but these were the most useful
hope thats useful
CHris
www.chrislong.me.uk