The Homeschool Buyer Co-op is a free homeschooling organization for both new and veteran homeschoolers.  Co-op membership is free and confidential, and entitles homeschooling families to GroupBuy discounts on high-quality curriculum.  On the site you'll find lots of free information, such as databases of free curriculum, field trips, and educational contests and scholarships. Highly recommended. 
I have enjoyed trying new curriculum this way and often the group price is discounted enough to truly make it worthwhile.  Additionally, there are trials so you can try before you commit.
I do appreciate the reviews from parents who have tried the product.
One of my favorite perks are the Homeschool ID cards.  I have been able to use these cards to get retailer discounts and for my son who needed a student ID at a testing center.
Click here for more information.