Just a couple of addictive online games I play when I really should be doing something else. They are free and don't require any form of sign up or account creation.
Boomshine:
http://www.k2xl.com/games/boomshine/
This one has been around for almost 10 years. The rules are easy, but strategy is difficult ... at least, for me!
Cat Bowling:
http://www.brandextract.com/catbowling/default.asp
Another game I have been playing for years, but only in October. Due to the Halloween seasonal theme it's only up for the month.