offers a wide range of information for businesses. Their section on Corporate Formation has extensive information and forms necessary to set-up the the different business entities.
To access Corporate Formation information you will need to agree to their disclaimer before entering that section of their site.
A short article that summarizes the differences can be found on CNN.com:
LLP, LLC, S-corp and C-corp: It’s not just alphabet soup! A breakdown of what you need to know, in layman’s terms.
bplans.com – business plan articles, tools, and free sample plans.