Was talking with @Voxybuns about an in-dev game of theirs, and they had an idea of giving a player an in-game reward if they were first place in a leaderboard by the end of the day. Currently though, there's no real way to check for this kind of thing conveniently.
It would be cool to have a "rankYesterday" number included within a call for the player's personal best — if they submitted a score to a daily board on a given day, then their final rank at the midnight GMT changeover could be logged server-side for a day, and the game could snag that info if the player logged in to peek tomorrow.
If the player didn't submit any score on a given day, or they're trying to get their best for a non-daily board, then it could just return nil or somethin'.
For instance, using the example described above...you could have a daily competition where you play one round a day, submit to the global leaderboard, and then come back tomorrow — if your "rankYesterday" returned 1, then the game would know that you finished first place out of everyone globally yesterday, and could give you a local prize.
Could also be used for stat-keeping (at least, assuming that the player would be checking in every day to e.g. keep a streak) — then the game could know definitively what rank the player wound up in at the end of each day, and keep track of it locally for some cool game history.