Once you have a website that receives over 1 million views a month, the cost of hosting can rack up, especially if you're a very heavy image based site like UltraLinx is.
CDN services can help bring down the cost a little, take off the load of your server and serve your images faster. However nearly all CDN services you have to pay for of course, as your files on are on a server which is using bandwidth.
There is a neat feature in the Jetpack plugin by Automattic, the creators of WordPress. Not many seem to know of the Photon feature that comes in the Jetpack plugin. This feature may just be the best thing ever for content heavy sites. Photon is a CDN by Automattic. It caches your images on the WordPress.com servers and delivers them for you. This reduces the load on your web host. And the best thing about it, is that it's completely free.
You just have to have a WordPress.com account (free), install the Jetpack plugin and sign in. From there you can just activate it and it'll take care of the rest.
UltraLinx has over 14,000 images on the site. I'm hosting with MediaTemple. When looking at my bandwidth levels last month, I only used up 400GB out of my 1TB limit. If I didn't have Photon on, I would end up using well over my 1TB limit, which would of course mean paying more, and it'll be a massive strain on my server.
If you have a self-hosted WordPress site, install Photon right away. It's one of those gems which most people don't know about but can easily save you a huge load of money and limit the strain on your server.