Hi Davida.
The site is all custom coded (by my husband) and I create the ads myself using Photoshop or Fireworks (or, outside ads are provided to spec by the person creating them), then my husband dutifully puts them in the sidebar for me where I want them to go. Because we have a directory added on to the forums themselves we have to code in two places for the sidebar.
I'm sorry it's likely not the answer you were hoping for, but with a little knowledge of HTML any simple website can be 'divided' up into columns with a sidebar on either or both sides. Many blog programs come this way already as well.
Let me know if there's anything else I can help answer for you in this direction