What about, say, an optional sidebar for widescreen monitors, which a person could fill with widgets that hold a secondary importance to the site. Things like RSS feeds. And only show that to people who have the room to accommodate it.
I really wish that more of my screen space could be used. I'm at 1600x900, and WordPress doesn't take up more than half of the available space.
I've noticed that WP blogs look great on tallscreen monitors. I just hope that those of us on widescreen will get the chance to make use of that feature.
The blog I need help with is actionary.wordpress.com.