Quakelive is down and I finally got some time to implement a script for QLRanks.com website. At the moment being, it works only with Firefox and Chrome. The compare feature is simple: go to a player profile, add it to the compare list and hit the "compare" button.
The initial release works only with duel stats and maximum with 2 players compared. Possibly I'll extend it also for other game modes. Any bug report/feedback is much appreciated.

PS. I'm not affiliated with the original QLRanks.com team, the compare feature is a proof of concept built with QLRanks exposed public data. Have fun comparing :)