One of the best books I've read for ages is 'A Praying Life'. Well now you can get it for free if you go to amazon and download the kindle version; . But you say I haven't got kindle! Click here Well you can download a kindle reader for your laptop or phone for free too!
It is a great book on prayer and one which I plan to re-read every 6 months or so. Its free so why not read it!