Java Applets
Some applets require later versions of Java (it's not 1998 anymore...) If you're running Windows with Internet Explorer, you'll likely need to download Sun's Java Runtime Environment (JRE). (Not sure where to click on that page? Google can highlight it for you). Here is why Microsoft no longer supports Java.
Assuming you've installed the plug-in and are running the latest version of your browser, these applets have been tested and work on:
A port of Minesweeper to Java - with a facelift and new features. It puts other versions of Minesweeper to shame.
A paper and pencil puzzle in which you must deduce the locations of the hidden ships.
Another paper and pencil puzzle in which you must connect the dots following specific rules.
A port of the popular Minesweeper game to Java. This (lighter) version should run in older browsers as well.