Remember a few months' ago when I mentioned one of my favorite time-wasters called Subway Scramble? If you haven't tried it yet, you can give the full version a try this weekend. GameBlast, which is the premium game service over at Shockwave.com, is having a free three-day trial this weekend sponsored by Sony. Because these aren't little Flash games, they are too large to play directly from the site. You download the game, install it, and then sign into the game with your username and password. It seems a little weird to download a single-player game but still have to be online to play it, but it's free so I am not complaining.
Besides Subway Scramble, I would also recommend Diner Dash and TumbleBugs. C1, who doesn't usually jockey for computer time with the other kids, likes TumbleBugs a lot. You also get access to those addictive Inlay games like Puzzle Inlay and Magic Inlay. If you have downloaded free 60-minute trials from Shockwave before and you still have them on your computer (who hasn't played Lemondade Tycoon?), this will give you a little extra playing time.
Unlike similar offers, you don't need to put in a credit card number so that they can start charging you as soon as your 72 hours has expired. I didn't see a way to access this particular offer from the front page, so try the link I provided above and see if it works for you.