If you have a baby, are going to have a baby, or know someone who does: Get a sling.
This is on the Things That Make Sense list, but rarely does it get mentioned on the Must Have For Baby list. Maybe that's changing now, since baby wearing is becoming more popular again. Even just four years ago, when Yonah was born, you basically had to settle for either a full on baby wrap (a long piece of fabric you used to literally tie the baby to yourself) or one of the backpack carriers not suitable for very little babies. If slings were publicly available in the US, they were literally in the one place I didn't look.
With such poor choices, it was understandably rare to see babies out of the stroller carrier systems. I still see a lot of babies in those today, but I also see quite a few in slings or even the newer front carriers. It's kind of like cloth diapering, which is now the "cool thing" to do as a young parent.
Baby wearing is a complete life saver. And it just makes sense.
Think about it. Babies spend their entire existence in constant physical contact with someone. Then they are born, and suddenly they are forced into a new environment where they can be, and are often, put down - the very concept of which is alien to them. A sling helps make the adjustment easier.
It also helps the mom's sanity. How many times have you wished for an extra set of hands? Moms wish that at least twice as often - probably more. Slings provide a means to cradle (and even nurse) a little one while leaving both hands free. (As a bonus, they also provide protection from that well meaning stranger who touches your baby's face; nobody wants to accidentally touch your breast.)