While some of the most popular online hangouts include Yahoo! Games and Pogo (an Electronic Arts subsidiary), other sites without the big bucks behind them are creating simple games that are hard to stop playing once you've begun. Among them are the aptly named Addicting Games, Cognitive Labs and One More Level. I can hear the kids' cries now... "Mom! Do I have to go to bed? Just one more level!"
My favorite by far is Addicting Games' Pinch Hitter. Having been introduced to it by some subversive friends at Athletics Nation, I've shared the links with family and colleagues, and am never satisfied with my results. While capable of hitting the occasional home run, I still have a tendency to strike out, which can severely damage my score. I strongly suggest you take a few swings yourself. If you do play, be sure to post your high score in the comments. Only on rare occasions can I top 25,000.