Coffee

From mercola.com:

Drinking coffee does have some well documented problems. For instance, it may interfere with your body's ability to keep homocysteine and cholesterol levels in check, most likely by inhibiting the action of the vitamins folate, B12 and/or B6, for one.
Additionally, coffee has been previously associated with an increased risk of stroke and rheumatoid arthritis.
So all in all, coffee is clearly not the healthiest liquid to drink—your healthiest choice is pure water--but coffee and caffeine are far less dangerous to your health than fruit juices or carbonated soft drinks.
If you do choose to drink it, though, there are several pieces of advice that you should keep in mind:
Pregnant women (or those who are breastfeeding) should always avoid coffee. Research suggests that drinking more than 300 mg of coffee daily, or the equivalent of two to three 8-ounce cups, may increase the risk of miscarriage, birth defects such as cleft palate and low birth weight.
If you decide to use coffee, please make sure that it is organic. Coffee is one of the most heavily sprayed crops, so drinking organic coffee is a smart way to reduce your exposure to toxic herbicides, pesticides and fertilizers.
If you drink decaf, try to select brands that use the "Swiss Water Process" decaf. This patented method is the best choice, as most of the major brands are chemically decaffeinated, even if it says "naturally decaffeinated" right on the container.
Avoid sugar and milk. These are actually much worse for you than the coffee itself. Don't compound the detrimental health effects by adding milk or sugar to your coffee.
Only use unbleached filters. The other bright white ones, which most people use, are chlorine bleached and some of this chlorine will be extracted from the filter during the brewing process.

And I'll add: be sure you're using good, clean, pure (filtered, NOT tap) water to make your coffee!