While not a "reusable" product, I wanted to do a focus on Allens Naturally Detergent as a great eco-friendly laundry choice. A favorite among cloth diaper users, this detergent is an excellent detergent for all your laundry. Good for sensitive skin, Allens has no dyes and no perfumes. There are no brighteners or enzymes, and Allens uses no animal testing or ingredients. In a further effort to be environmentally conscious, it's very concentrated, so there is less packaging and shipping weight.
I test out different detergents to have a good idea of what's out there, but I really love Allen's. I have an HE machine, so I use 1/4 of the recommended amount (1/4 is also the recommended amount for cloth diapers). That means a quart (32 normal loads) last for about 128 loads! It's a great value for a great detergent.
Allens offers a great product from a great eco-conscious and ethical company!