I have just spent a very happy hour on my day off absorbing Hot Shots: How to Refresh Your Photos: Kevin Meredith.
If your having doubts about your photography, think you need that extra piece of kit or look outside thinking 'its not the right weather' this book will go a long way to remind you why you like taking photos in the first place.
Designed as a quick reference how to using Kevin's portfolio and his collection of simple (and not so simple) cameras, the book goes through a wide range of techniques and mental checks which really hep you reassess your work.
Page layout is simple, and due to the explanation one page/photo the other on a spread, you read about the technique and see the result all in the same page.
Also as kevin is lomokev on flickr and a fellow brightonian, if your local you should get the book anyway to see some refreshing shots of our hometown.
All in all a happy, non patronising book for any skill level and should be kept handy for those days when you feel like not shooting to remind you why you should!