Since no one protested and some were interested, here is long awaited site that will host memrise unofficial leaderboard:
Q: How do I add myself/other user to the leaderboard e.g. user: neaz333?
A: Visit memstats.com/neaz333 and neaz333 user will be automatically added
Q: How often is the leaderboard updated?
A: It does not happen automatically or periodically. User stats get pulled from memrise servers once you click username in “Username” column, or visit memstats.com/ page. To prevent hammering of memrise servers, user statistics will be pulled only when at least 5 minutes have passed since last update of given user.
Q: What about streaks or per course points?
A: No public memrise API is available to do this unfortunately