Last week I was paying roughly $1 per trial download.  Now I’m paying $.50.  I hope by next week to be paying about $.30.

The secrets, such that they are, are mostly in the post right below: dropping non-performing ads, optimizing for CR instead of CTR, and tuning my landing pages.  Incidentally, I found another no-brainer: underlining hyperlinks, which is probably partially responsible for the a 10% increase in people successfully finding the trial.  (This is on top of the 100% increase I got from making that trial a button, but apparently some folks actually read the text I spent so much time writing…)