Correct Positioning Guide - especially helpful for newborns
The Babywearer
A great site for general information, forums, product reviews and vendor listings. The forum section also contains a "for sale or trade" section for buying and selling gently used carriers.
The Mamatoto Project
"The Mamatoto Project was created to educate the general public on the advantages of babywearing, and to promote the use of a simple piece of cloth as a traditional baby sling among those who care for infants and toddlers. We offer how-to guides for babywearing parents and caregivers. We discuss the advantages of babywearing with doctors, doulas, midwives and other health care professionals. We help coordinate babywearing classes and events. We coordinate the efforts of babywearing lovers to get wider coverage of babywearing in books, magazines and television.
Mamatoto is Swahili for the Mother-Baby unit. In that culture, babies are never seen apart from their mothers, so the two are considered one."
This site has some excellent demonstration videos for using a simple piece of cloth, or wrap style carrier.