Your ZIA's are beautiful and I just wanted to alert you to the 'official' website for Zentangle which is of course
www.zentangle.com There you will find a whole community of artists who love to tangle and create new patterns. Some also have a weekly challenge that anyone can participate in. I've been tangling for a few years now and have 6 art journals filed with zentangles. Susanne McNeil, inventor of the 10 minute block is an avid zentangler and has written many books on the subject.
http://blog.suzannemcneill.com/