Mum bought be a belly belt which I never used so that would be my least useful I guess?
My mum bought me one as well and I found it incredibly useful, I wore it all the time. Made my work pants & jeans last for AGES just with a long top over them.

Pregnancy pillow was ACE, couldn't have lived without it.

Least useful - anything ginger! urgh talk about making a girl want to spew!!