Furnishing the sidebar the honest way

I'm developing yet another website (non-blog, static), and yet again I'm stumbling upon the same problem with inner (non-home) pages design. The layout is conventional:

• 960px wrapper
  • header with horizontal menu
  • main content column + sidebar
  • footer

The site structure is quite simple, and the horizontal menu contains all the navigation items I need. The main content column contains several paragraphs of text. And then there's the sidebar area. I need it to be there for one reason: the main content can't be as wide as the wrapper, because its readability would suffer if it was 960px wide.

But there's no honest content I can think of putting in the sidebar.

There's no sub-navigation. I refuse to clutter my website with widgets like tag clouds, twitter feeds, ads etc: they would serve no purpose. Also, I don't have to promote any other content on my site, as everything is contained within the nearby horizontal menu.

I don't want to make the wrapper narrower: some bits of content within the site utilize the horizontal space fully (header, home page, some sub-pages).

I could put some illustrations in there, but they wouldn't be significantly related to the main text: it wasn't written with graphics in mind.

I could go for n-column layout for the main text, but technical difficulties aside, I don't think it's feasible with unpredictable viewport heights: scrolling down to reach the end of one column, then back up, and then again doesn't cut it.

(It makes me think though: maybe some clever application of <a href="#nextcolumn"> at the bottom of each column would make such a layout usable? But this needs experimenting on a different, and preferably synthetic specimen)

I'm reluctant to leave the sidebar empty, so as not to create a huge empty swath of unused space, even though this seems to be the most reasonable solution.

Any thoughts? I wouldn't expect definite answers, but some ideas maybe?