Assorted interesting and/or cool online games, toys, and puzzles:
- Gimme Friction Baby, which Charles D described as "sort of a cross between Missile Command and Curling." After it finishes loading, wait a bit for it to select the right game; once it shows the "Gimme Friction Baby" screen, click that. I'm not gonna tell you the rules; play around with it for a little while to see how it works. Fun and addictive, and each game is generally short. Bizarrely, sometimes when you click that link it takes you to a description of the game rather than the game itself; if it does that, skim down to find the link with the name of the game and click that. (You can read the full description if you want, but I think it's more fun to figure it out for yourself; pretty easy to figure out.)
- Can you name all the US Presidents in ten minutes? Last names only, which means that some names will get you multiple Presidents at once.
- Statetris-USA: Tetris with the 50 US states. Higher levels do things like remove the state-name labels.
- Falling sand game. No goal, no scoring, no victory conditions; just a cool toy. Fairly self-explanatory; the main thing I couldn't figure out on my own is that "Cera" is wax, which burns slowly when set afire.
- Gravity Pods, sort of a puzzle game. I eventually made it through level 40, out of 50 total. Levels take anywhere from a few seconds to tens of minutes to figure out.
- Acrobots: another fun toy.
- Desktop Tower Defense, which is much more complicated than anything else listed here, and requires much more remembering of rules and working out strategy and such. I only played it once or twice and it didn't do much for me, but several of my friends got really into it.