World Wide Quilting Page: http://www.quilt.com/MainQuiltingPage.html
You can search under a variety of topics; also includes chat pages, and commercial quilting sources.

Free Quilting Lessons with Joanne: http://www.sew-whats-new.com/quiltlessons/index.shtml

Quilting Tips by Cottonwood Quilts: http://www.cottonwoodquilts.com/quilting.htm

Quilting Lessons by Debbie Kratovil: http://www.quilterbydesign.com/lessons2.html
38 ways to better quilting

Atlantic Fabrics Quilting Tips: http://www.atlanticfabrics.com/quilt.html

Dawn Pages: http://www.reddawn.net/quilt/quilting.htm

Online Lessons: http://www.kathkwilts.com/lessons/index.html

Machine Appliqué: http://www.critterpat.com/back2basics.html

Hand Appliqué: http://www.quiltsville.com/Applique/Applessons.html

Red Dawn Pages: http://www.reddawn.net/quilt/quilting.htm

Jinny Beyer Studio: http://www.jinnybeyer.com/index.cfm
Well-organized drop down menu

Paper Panache: http://www.paperpanache.com
It's a great paper piecing website, with regular mystery blocks, free patterns as well as pattern to purchase.
Recommended by Judy for those who love to paper piece!