Back tot he topic, I found the following:
That appears to support my recollection that the +1 stuff originated
with Slashdot or a related forum. It was used as a voting method to
increase a post's score (or decrease, if -1 was used) which determined
how visible the post was.
Yes, thanks. That pretty much answers my question.
"So [Trillian], two heads is what does it for a girl?"
"...Anything else [Zaphod]'s got two of?"
- Arthur Dent