My son is planning an RTW trip on not enough money next year. I'd like to get him a book or two for Christmas on how to travel on very little money. He's thinking SE Asia, India, Turkey, and a jaunt through Europe (yeah, I know, that's going to be the tough part to do on a shoestring). Any book recommendations you have would be appreciated. Thanks.

Well given that LP does a whole series of Shoestring guides and given that you are on their website and given that if you click on their online store to the right of this response you can order them right this minute, maybe that would be a good place to start.

Here are some I purchased before I lefts
Rough Guide- First Time around the World- I really liked this book, easy to read and had allot of good information
The world's cheapest Destinations- you can get it on their webiste. THe Inforation may be a bit outdated but I think it lists the destination you mentioned above and may help him look at other cheaper places. I found this book helpful when trying to chose my places that matched my budget.
This is a great website for general Around the World and a book list you might want to take a look at.
http://travelindependent.info/books_planning.htm
http://www.worldscheapestdestinations.com/