I think I've found what just might be the widest graphic on the Internet. It's the Solar System with the Sun and all the planets shown in a scale of 1 pixel = 1,000 km. It's not just the Sun and the planets out to Pluto (I think this was made before Pluto was demoted to dwarf planet status). It includes all the space between as well.
To get some idea of how big this is, I started on the left side and began scrolling by holding down the right arrow. At first it didn't look like anything was happening after the Sun scrolled off the left of the screen, but eventually a small image slid into view. It was Mercury and since it's to scale, there's not a whole lot of detail. I kept going and eventually Venus slid into view. More patience, then Earth and later Mars. After Mars I had to pause while I listened/watched LiveIreland.com with Klara McDonnell.
When I got back to the Solar System and resumed scrolling, I figured it had taken about 20 minues scrolling time just to get out to Jupiter. That's only about 1/7th of the way across, meaning it would have taken close to two and a half hours to get all the way over to Pluto. WikiAnswers says Pluto averages 328 light-minutes from the Sun, so that would mean the scrolling speed on my computer is about twice the speed of light. I guess that's pretty close since WikiAnswers says Jupiter averages 43.8 light-minutes from the Sun.
The Hitchhiker's Guide to the Galaxy has this to say about space:
"Space," it says, "is big. You just won't believe how vastly hugely mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist, but that's just peanuts to space."
When you spend 20 minutes scrolling at twice the speed of light to get from the Sun to Jupiter, you begin to get an idea how big the Solar System is, and that's far less than peanuts compared to the galaxy, which is immensely tiny compared to the universe.
It would take over two years of scrolling at the scale of the Solar System graphic to cover the distance to Alpha Centauri, by the way. I think my finger would get tired.