Ok, the Google ad will not show on the home page or category page, only on topic pages. Scripts from another ad provider does not work and the side will not load. The HTML widget, me thinks, should be able to render any HTML/JS script.
Popular Tags Widget
Here is another widget, this one displays the popular tags in your forum. You can set how many tags to display in the widgets ACP.
Nice, How about a 3D tag cloud plugin?
(click on Create Sphere 3D)
Both suitable for different niches. Though I love second one, I will be choosing first as it is more suitable in my kind of forum.