Things like this really challenge the imagination.
Eventually scientists say our own sun will expand to encompass the earth's orbit. That is unimaginably big. But the stars shown in this great info-graphic video, are really is amazing. I can't comprehend how these massive stars even exist. Their boiling atmospheres extending well beyond Mars or even Saturn if they replaced our star.
A remember, as big as they are, these are insignificant specs of light in a galaxy of 100 billion stars, and a universe of a 100 billion galaxies.
Youtube is full of these videos. Most with different music but here is a similar animation of stars sizes.
I can't close this post without a link to this article that started my thinking today:
http://www.universetoday.com/2008/04/06/what-is-the-biggest-star-in-the-universe/