Contests extended by another 24 hours.
I'm concerned by these arbitrary contest extensions.
If I'm winning and you just decide to "extend" the contest, I'd be pretty upset...
Unless there is some problem such as a downtime, you should never do that.
Instead, if you "extend" them because the players were too few to complete the contest, you should reconsider the contest rules.
(for instance, instead of random arbitrary extensions and contest expirations, you could say that a contest is over when it reaches X players, and that after a given date any player can decide to abandon it and you reimburse him the fee)
Finally, which measures do you use to prevent cheating?