I own a forum, http://webmasterforums.net46.net, and my CTr is slowly dropping on this forum (I know it's not very active but CTR should remain the same). Is there any method that anyone here has tried to increase their CTR that has worked on a forum? Someone suggested that varying the colors should help, has anyone tried this?

Hi there

You have got your ads in the best place on ur site, you could try changing the colour to try to attract more people to it, it does work sometimes, but it looks fine to me.

Im afraid its probably going to be the lack of people using your forums that is causing the problem, as the regular people who use your forums, probably wont click the adverts, so unless your getting new people over and over, your clickthru will go down.