Ah, the time of 16x16px icons. I used famfamfam until I discovered fugue, which had a similar aesthetic but three times as many icons and many more badges for making variants.
Sadly these icons aren't scalable for sharp rendering on HiDPI displays. I tried running xBRZ on them, but the icons are too blurry/antialiased for the algorithm to really know what to do, and the output is a blurred mess.
Agreed. So popular back then, but gorgeous and neat. Their flag set was also my go-to choice until I switched to Apple Emoji flags as images.