I have no clue how much the .ps extension is worth or what is stands for. But I would try contacting carbon poker(owners of poker.com) and try to sell it to them. Maybe get like high $XXX to low $XXXX.
tough, it's obviously an awesome keyword but I haven't heard of any notable .PS sales. Can't say more than high $XX - low $XXX right now. But like slutz said, you're probably better off holding on to it.