Well i have a forum at http://bestearnonline.com and i have only been using adsense for a few weeks on the site but i am not sure if my members actually even notice it. I have a thin bar under the first post of every topic in the threads as i didn't want it pushed in to peoples faces but now i am not sure if it is a wise idea. Any feedback will be appreciated. You don't have to sign up to see the adsense.

Forums dont have such a high CTR so i dont think a link unit will do you much justice.
I would suggest putting a 728x90 image ad in place of the link unit you already have up this way you get paid for impressions as well as clicks.

P.s I would also center the ad that way its not all the way to the left like that use this <center>YOUR AD CODE HERE</center>

Hope this helps you Good Luck

yes thank you very much MoneyMan

I agree with MoneyMan on this this will improve your Clicks / Page eCPM (cost-per-thousand impressions)