Are there any positive effects of caffeine?

Caffeine is well recognised as increasing both alertness levels and attention spans. A cup of coffee or tea is often recommended to counter sleepiness, especially for those driving long distances and many people resort to an afternoon "cuppa" to get back on top of their workload. Studies have shown that caffeine may also improve memory and logical reasoning.
Many caffeine-containing beverages, most notably tea and more recently coffee and chocolate, have been found to contain antioxidants. Antioxidants appear to have health benefits especially in the area of heart health and cancer prevention.
Recent reports suggest that caffeine may be useful in treating allergic reactions due to its ability to reduce the concentration of histamines, the substances that cause the body to respond to an allergy-causing substance. More research is need in this area before conclusions can be drawn however.
Caffeine has long been known to help some people suffering from asthma.