Our logo was made by the talented Matthew Stevenson. You can find his online gallery here: http://dcmjs.com.
We had first gotten to know Matthew's work when we saw him post a series of great class icon designs to reddit. We later contracted him to design a t-shirt logo for our guild, and we even briefly met up with Matthew at Blizzcon 2015.
Aspyr and Ulsoga had been itching to build another WoW community fan site, so when the ideas for Raider.IO started brewing, Ulsoga contracted Matthew to design a few logos for the site. What you see here is the one we picked! :)