Quaranta Settimane Babywrap

Absolutely brilliant. Long stretch of jersey that gets tied in various different ways (excellent booklet shows step-by-step instructions for about 8 different modes, depending on the age and inclination of the baby). It was the only thing that helped when our newborn suffered from colic. At three months he loved being carried around the house in a big hug. Now at almost six he grins a big smile and puts his hands up whenever I put the sling on. And in the mirror I can see his delighted face.
Easy to transport (comes with pouch that is slightly larger than a paperback when full), easy to wash, even easy to knot once you have practised 2/3 times (this comes from hugely inept person). The only thing for which we do not find it so practical is airports: preparing the sling takes a bit (2 mins), so not ideal if you are going through the airport on your own and need to take the sling off and then put it on again. We use a structured carrier for airports (but baby dislikes it).