Cool tool. The down-arrow seems to jump every-other font on the list. It'd also be good if it automatically loaded the font as you pressed that key to go down the list so you could quickly pan through them all without a lot of clicking.
I was supposed to add code to change fonts with up and down keys but it was getting a bit complicated for JS noob like me so I dropped it for now.
It'll be added in next version for sure.