Since this place seemed lonely, thought I would post a few of the guides/sites I run to if I want to look something up or just browse.

Getting Started With Dimensions - This one is nice if you are a total newbie to dimension building and gives you an idea how to get started.

Rift Decorators - A dimension database.

Better Homes and Dimensions - The page I directly linked tells about the different dimensions and what they contain including item limits. If you are wondering which dimension to build, this can help you. Also other helpful articles on the site.