Welcome to WebmasterWorld Guest from 18.104.22.168
Forum Moderators: not2easy
Most of the ads I have seen that size are Flash movies. They allowed users to explore the ad and get more information before clicking through. I found these nicer than just a large picture that is clickable. It allows me to go only if I am interested and I think would give you a more targeted visitor.
If you want examples then sign up for yahoo mail. They throw these in all over the place.