Just use this method David.
http://forums.macrumors.com/showthread.php?t=206117
See how the banner is enabled for guests, but not members?
but since I never sign out that means David will receive no ad revenue from my visits,
which is odd when you consider that I'll keep coming back whilst guests might not.
e.g, a single guest might use perhaps 1MB, in a month, and see enough ads to cover the cost of that.
but if you turn ads off for members, then we continue to download perhaps 30MB a month whilst not helping to generate any revenue.
Yes, something like that.
If you guys really hate it, Adblock will block it easily.
like was said a while ago, it's a very small rectangle, it's not intrusive, it's not for bad products. and it's a small thing to ask you to use a few K of your bandwidth to get a small button that isn't all that noticeable to generate a few pennies to help keep the site open.
I think that I could say for sure that if this was my site, I wouldn't want to run the site at a loss paying out of my own pocket so a group of people could chat on-line about whatever took their fancy.
I doubt that David will want to pay for the privilege of letting us air our opinions here either.
viewing a small ad isn't so much to ask IMO.