First, this is not about gypsy jazz but I found it very useful. Seems to me that sometimes we forget this music is jazz after all.
The Vanilla book:http://www.ralphpatt.com/index.html
Is an on-line free book with the basic (no substitutions) changes to a bunch of jazz standards.
The website also features some downloadable backing tracks and other fun stuff.
The Jazz handbook:http://aebersold.com/Merchant2/merchant ... =_HANDBOOK
Is a downloadable (page by page) book full of great advice and tips for playing jazz. Check out the story about Charlie Parker, to remind you that the greatests masters were beginners once, too.
It`s written by Jamey Aebersold who is famous for producing the finest playalongs for jazz, you can get all of them at this site, no Django playalong yet, though.
Let me know what you think.
I hope you`ll like them.