The U is an educational region for OpenSim and Kitely in particular. Tutorials and notecards about navigation, shopping, building and hypergating, mentors, gates to destinations on both Kitely and other grids, and more. Hypergrid visitors welcome.
A sandbox region on the Great Canadian Grid, conveniently equipped with a set of Linda Kellie building tools, licensed CCO for any use whatsoever. Includes scripts, textures, templates, and sculpties. There is also an OpenSim building tutorial here.
A freebie region on the education-focused Jokaydia grid. Building and landscaping supplies as well as avatar clothing and accessories, poses, animations, many from Linda Kellie, ReactionGrid, and other education-friendly sources. There is also an excellent OpenSim tutorial area on this region.
Home of the OpenSim Builders Alliance on the Littlefield grid. Region includes several classrooms, and collections of free building materials and scripts. Some content is not exportable, however. There is a Blender Q&A with Aaack Aardvark every Sunday at 2 p.m. Pacific time.
An education-focused region on the Craft grid, home to weekly scripting and building classes.