For example, if someone has a thread where only two other people respond, it's clear they aren't creating much discussion, but if a thread has several different users who respond, it would be an indicator the thread was generating more views for the site itself - and I think users should be rewarded for this.
My idea:
+1 akorn for every three users who engage with a thread
+10 akorns for threads that make it past 4 pages
There are probably some loopholes with this, such as people using taglists to have their friends respond, but I think that would also mean nicer users who are likely to have more friends and positive engagement with the site will receive compensation for making AKP a more kind place. You could also enforce a rule where threads that utilize taglists don't receive extra akorns.