I visited some blogs and found the 125x125 banner ads displayed on their sidebar. I pointed my mouse to one of the 125x125 banner ad, it showed the url of the blog domain name instead of the real destination url. Then when I click on the banner ad, it will like re-direct from the blog domain url to the destination url. Here's an example of the blog: http://www.dailyblogtips.com/ How to they do this? Any tips from expert will be appreciated.
This is done using many link cloaking plugins and scripts. If you're using WordPress then try gocodes wordpress plugin.