I grabbed their "official" list from http://www.gnu.org/order/ftp.html, did some grep + sed job, and verified the final list whether it's working. Out of ~140 sites, only 91 do actually work. The rest has no DNS records, does timeout, has empty/missing mirror dirs, requires authentication etc. Bleh. :/ See the attached cleaned-up list and commit, please.
Created attachment 94917 [details] verified GNU mirrors list
Done