I tried to make the "sling" listed at http://www.kanggah.com/cheap/sling.html -- unfortunately, the pattern currently posted online is actually for a big hobo bag. I wrote to its author, Maka, and she said that she had in fact modified that pattern to make a baby sling, but the modifications were not included on that page. Here's how mine turned out. Needless to say, I unravelled the whole thing and used the yarn for a different kind of bag. Additionally, a bag-type sling can be dangerous for babies -- please read about positional asphyxia, which is a true risk any time a baby's chin is forced forward onto her chest. I have asked Maka to remove the directions, but as she has not, I will leave this page here as a caution.
I have removed my own crocheted pouch directions because as babywearing has grown up, we've learned more about what makes a safe, comfortable carrier, and what should be avoided. While I felt the pouch could be safe for limited use (only with bigger babies, 6 months and up, and only if it's crocheted very tightly so that it doesn't stretch too much), there is too much potential for error, and I can't guarantee that a new parents with novice crocheting skills will do what they need to do to use it safely.
PLEASE do not use the Maka sling for carrying babies. It makes a fine bag, and you can certainly use it for carrying baby's things, but it is NOT safe or appropriate for carrying babies. In addition to the very real and unfortunate risks of positional asphyxia, a single snag is all it would take to unravel the bag and cause injury or even death to the baby. You can make a crocheted carrier for a child to use with a doll or stuffed animal, but please do not use one with a real baby.