The IRC channel I'm in most of the time has a karma system.
#pdxtech:someone> donpdonp++ #pdxtech:karmabot> donpdonp has 13 karma
With the rise of dogecoin, its a useful experimentation platform. There are way more coins and they cost next to nothing so its simple to experiment with micropayments in whole.
The giving of karma remains the same. A new bot talks to a dogecoind process to get the pool total and issue payments. There are a variety of systems to allocate payment. What I am going with is to calculate each user's karma percentage of the total, then use that percentage against a daily payout total.
Karma is payed out every night, also if a payment happens, that user's karma is cut in half. The goal is to provide some kick-back for a short amount of time, then reduce to zero until the next karma is earned.
update Mar-2014: the karma system is implemented in simplified form. a single doge is given out (recently raised to 5 doge) for each karma awarded, with a cap of 3 karmas per hour.