It would never, until I heard about this recipe, have occured to me that you could make chocolate sorbet. An ice-cream maker can be used instead of freezing/beating/freezing as described below. Follow manufacturer's instructions.
600 ml / 1 pint water
125g / 4 oz caster sugar
60g / 2 oz cocoa powder
100g / 3 1/2 oz plain chocolate, broken up
Put the water, sugar and cocoa in a saucepan and bring to the boil, stirring occasionally. Simmer gently for about five minutes. Remove from the heat and add the chocolate, stirring until the chocolate has melted. Leave to cool, then freeze until slushy. Stir the mixture until smooth, then freeze until solid.
Remove from freezer 5-10 minutes before serving to soften. This sorbet melts quite quickly.