Can this information be used in articles, essays, academic papers, etc?

Of course. It's publicly-available information and the original sources are listed on the main page.

Who made this?

A good 99% of the back-end code was written by Ian Webster (typpo). The code he wrote is open-source and available on Github. All credit for the functionality goes to him.

The design of the site is mostly just stock Bootstrap 3 CSS/HTML, with some minor modifications and enhancements. Those mods, this domain, and most of the text on this site was written/built by Mitcz Marzoni.

Why make this site when a similar one already existed?

I wanted a good exercise to learn some basics about Node.js, I wanted it a bit more mobile-optimized, I think "InTodaysDollars" is a better name for the site, I thought it could use a litle SEO makeover, and hell... why not?

Is there a copyright? Can I do the same thing?

No copyright of any kind. The whole thing is open source. Go nuts. I even forked this particular set of modifications to the original, which is available on Github. Apologies that I'm terrible at Node.js, so my modifications are probably quite sloppy.