rogerd - 11:24 am on Dec 7, 2005 (gmt 0)

Your forum software probably has conditional logic built in, e.g., it tests for a logged in user and displays different content depending on status. (An unlogged-in user may get a login box, for example, while a logged-in user may get a "welcome" message and a private message count.)

You could use this logic in conjunction with ad rotation software - call a different ad group. The visitor ad group gets all ads - the member ad group gets ads and blank graphics. Most ad rotators let you set the frequency of each ad.

Or, you could build some simple logic into your code. I just did this in a forum where I needed to synchronize two ads on the same page and the ad rotation software alone couldn't handle it. I used a random number function and a conditional to create a simple probability distribution, and set the page code to request particular ad groups based on the final number.