I am a lifetime member of the following sites
(some allow tubing...no special license is needed)
Tinsel Town
Simply Tubes
Roxane's
Roxane's Dreamland Tube License
Gypsy Pixels
Angelic Designs
Pixel Patch
Sassy's World
(site is closed)
Tuts and Lines
Tube Town
Pixel Hugs
Glennda
Majestic Country Graphics
Folk Art Treasures