Moderate drinking (1-2 drinks a day) can reduce your risk of heart disease by increasing HDL cholesterol, reducing the formation of artery-clogging blood clots, and quelling the inflamation that can contribute to heart disease.
Those who consume one drink every day are 54% less likely to be obese than nondrinkers. The same study showed that those who drank two drinks a day (or less than one, but a few per week) also have a lower obesity rate than nondrinkers.
Harvard researchers found that guys who drank moderately had a 36% lower risk of (Type II) diabetes than those who didn't drink at all.
Beer contains polyphenols which have been shown to help slow the growth of cancer cells and boost the body's production of cancer-fighting enzymes.
Booze makes women prettier, men smarter and linguists more fluent.
(Okay, that last one is just personal experience, but the other bits are from various articles in Men's Fitness and Muscle & Fitness magazines. 'struth.)