I'm sure a lot of you folks know a lot more than me about this topic. THese resources have helped me a lot.From Song CHALLENGE 58, SharonA asked me to start a thread listing the recources I have been using to learn to write songs. While I have read literally dozens of books, articles and websites on the topic. I keep going back to the same two books both of which have been invaluable.
Songwriting and the Creative Process by Steve Gillette and Acoustic Guitar magazine's private lessons. I bought both books but you can get much of the information for free from the following websites.
http://www.acousticguitar.com/lessons/
http://www.sover.net/~gillette/