These links appear in the "Featured Sponsors" box in either the left or right column of all pages of the above 3 websites. That's PR6 websitegoodies.com, half a dozen or more PR5 pages, and lots of PR4s.
One of the current links in the box has expired and will be replaced with yours; it's not getting bigger. Please take a look at the available size before purchasing, and pay here if interested: PayPal Subscription.
First come first serve. I will post when the space is gone, and if two people happen to pay at the same time, the second will be refunded. These sites receive over 500 uniques a day.