On some other forums there is the option to 'thank' a poster for their post withouth having to post a new post.
Is this function available?
Not exactly.
There is a karma system that I have not enabled:
"Karma is a feature that shows the popularity of a member. Members, if allowed, can 'applaud' or 'smite' other members, which is how their popularity is calculated."
More
info about the system.
I don't want to have popularity contests on the board. I'd rather leave the Karma system off.