The Mamatoto project. Their website has tons of pictures and videos and instructions for wrapping, teaches how to make your own wrap or other carriers (no sew instructions also available) and lots of other babywearing help. Don’t forget to make a donation if they help you:
www.wearyourbaby.org

The BabyWearer website is a great place to get all of your questions answered. Hundreds of slinging mamas ask questions and offer each other answers on their many forums, and generally share babywearing experiences. Until you peruse these forums, you cannot know how many different carriers are available in each style (wrap, ABC, ring sling, pouch) all with their own extras. You can also find carriers reviewed here, and get a good deal on a used carrier on the for sale or trade board:
http://www.thebabywearer.com

FreeHand Baby, LLC offers beautiful custom handmade oriental style baby carriers including mei tai, hmong, onbuhimo, and podegi. They also offer a baby carrier made completely from organic cotton.

Dr Sears, the original attached parent, goes over the benefits of babywearing:
http://www.askdrsears.com/html/5/T051100.asp

One mama’s instructions for one shoulder (short-wrap) carries:
http://www.cs.cmu.edu/~elly/rebozo/

The Rebozo Way Project is bringing back the lost art of the rebozo (shawl) carry:
http://www.rebozoway.org

Here are a list of studies, books and articles on babywearing, from the Rebozo Way site:
http://www.rebozoway.org/articles/studyiap.htm