It's not easy to do, but it's something I can look at in the future. One concern is that it would hamper site navigation, since you'd no longer be able to go directly to other parts of the site. That's also where we show who's in chat, and it's necessary for that to be a bit in your face in order for people to realize that the chat room isn't empty.
Part of the problem with the images going off the right is that the resizing codes from old posts don't work now, due to differences in how bbcode is interpreted.
Other people have requested it too, though, so it's definitely something I'll look at when I get to working on the visual design iteration a bit down the road.
FYI: I have a 30" and a 20" monitor at work, but at home I use a 13" macbook!