I would recommend that you/they read "Clean Code"
http://www.amazon.co.uk/Clean-Code-Handbook-Software-Craftsmanship/dp/0132350882/ref=sr_1_1?ie=UTF8&s=books&qid=1251633753&sr=8-1
The basic idea of this book is that if you do not keep the code "clean", eventually the mess will stop you from making any progress.