Ginger Beer

1 whole gingerroot 
1/2 teaspoon yeast 
3/4 cup sugar 
15 cloves 
1/4 teaspoon anise

Take about a half-cup of warm water, and mix with sugar. Then sprinkle yeast on top. Let sit. 
Boil about 2 litres of water. 
Peel the ginger root and cut into smaller pieces. 
When water has been brought to a boil, add the ginger root, cloves, and anise. I like to put the cloves in a small tea ball so I can remove them easily later. 
Boil for 30 minutes. Then remove ginger root and cloves. 
Dissolve 3/4 - 1 cup of sugar in the brew. 
Let the brew cool until it is tepid (ie won't kill the yeast). Then add they yeast mixture to it. 
Now pour the mixture into a 2 litre plastic bottle. Top up with water. Make sure you leave between 5-8cm of air in the top. Play with this amount -- you'll find you get more pressure if you leave the air inches. 
Now leave in a warmish place for about 1 day. Watch it carefully the first time - wait until the pressure has built up, then refrigerate. 
Leave in the fridge for at least 2 days. If you leave it in longer, you'll get more pressure -- I usually leave it at least 2 weeks, but it can stay in there for 2 months. Still, it will continue to gain pressure in the refrigerator. 
When you open the bottle, be very CAREFUL! The pressure should be very high by this time. It's best to do it over the sink or outside, and do NOT aim at anyone! If you cover the cap while you open it, it will muffle the "pop". Instead, don't cover the top of the cap, but only touch the sides of the cap while you open it. In this way, it will fire like a gun. 
If you've got good pressure, it will bubble out like champagne, so have glasses on hand to pour right away!