I know that there have been threads on this in the past.
My youngest was given an amber teething necklace when he was born. He wore it until very recently (he has 8 teeth and has just turned 1). He's not wearing it now because I keep forgetting to put it back on after his bath.
I really believe that it was helpful. Plus I just liked it, it looked nice on, he never grabbed at it, and it is groovy. I also liked that it reminded my father of his memories of his Polish mother and her amber jewelery.
I am ready to try one, too! My dd has been teething since 4 months, now has 4 teeth, and only occasionally do we have a "good" day. Mostly she's crabby and needs soothing all day and all night. I truly believed in homeopathics, but they do not work for her. I have tried every single and combo remedy for her, to no avail. So I am breaking down and buying an amber necklace.