Here are some links you may find useful.
The Official Zentangle Website
Subscribe to the official monthly Zentangle newsletter
YouTube channels:
Zentangle
Design Originals
Sakura of America
Challenges:
Laura Harms' Weekly Zentangle Challenge
Celtic Challenges by Judy West
Erin Koetz Olson's Zendala Dare
Communities:
Line Weaving Community
Yahoo group: Zentangle-Inspired Art
Facebook group: Friends of Zentangle
Facebook group: Tangle me a Dream
Facebook group: Zentangle
Sharing Artwork and Patterns on Flickr:
Zentangle group
Freehand doodle patterns
Handmade Mandalas
Resources:
All my Weekly Roundups
TanglePatterns.com
Book: All Tangled Up by Cherryl Moote
Template for tile-size cube box
Pat Ferguson Quilts
Celtic Knots resources:
Celtic knot tutorial: Page 1, Page 2, Page 3
Celtic Knots by Jo Edkins
Lets Draw Celtic Knots from Fantasy Art Resource Project
Make Celtic Knotwork from thinkythings.org
