MinerGate mining pool. My co-workers and I all haven't running on our machines at the office during our downtime (evenings/weekends/lunch). It's great.
Tossed it on a couple of dev/stage servers as well. ;-)
Have it running on a few old phones I never threw away, because why not. And of course on my regular phone when I'm sleeping/etc and don't need the county power for other things.
Happy mining!