Here is a fun time waster: head over to http://erkie.github.com/ and drag the bookmarklet on the page to your browser’s bookmark toolbar. Then just visit any website and click on the bookmarklet. A small triangular spaceship should appear that you can steer around with the arrow keys. Press space and it will start firing bullets which destroy any page content it hits accompanied by fireworks display and sound effects.
A counter at the bottom keeps score of positive hits.
Now here is one trick. Click on the bookmarklet once to load a ship. Press the arrow keys to move the ship aside a little. Then click the bookmarklet once again, and lo!, another ship appears. You can now move and fire both the ships at the same time. You can load any number of ships you want for greater firepower.