What is the best way to display lots of images on a wordpress site?

I am working on a site which has a lot of really large images and it is bogging down the site. I would like to know the best way to host images somewhere else and link them into my site. What is the best method? What service should I use? If you are displaying an embedded image hosted somewhere else, is there anything special I need to do to style it so that it will be the exact size I need?

Thank you.