My company is not registered with the BBB, however we (based in Canada) are a member of a local Chamber of Commerce and have been pleased with the affiliation. It's true that pretty much anyone with the annual fee can join, so it certainly isn't exclusive.
However, I've landed a couple of customers since joining (6 months) and have networked sufficiently with other members to get deals on services our firm uses (i.e. printing, rental cars, group insurance, etc).
So, for us, the association with a Chamber of Commerce was well worth it.
Hope that helps