The sling allows you to carry the baby in several positions. Rose loves to "ride" like this...

This light blue one is a Nojo brand. You can find them at Wal-mart. We bought it recently at a yard sale for $2.

This is a picture of me carrying Rose at a recent Festival. After the first few minutes of looking around and smiling at people she was happy to snug in and sleep for a long time. I just can't say enough about how comfortable it is to "wear" your baby this way. I was also able to protect her from the sun. The black one is a SlingEZee by Parenting Concepts. This one is my favorite. It comes in small, medium, and large. I was also blessed to find this one second hand several years ago.
I plan to join Sarah at Fiddledeedee for more favorite things!