I've gone cold turkey on caffeine a couple of times (takes me about a week of headaches, I'm not an especially heavy user), mainly because I was making hot drinks to avoid work out of boredom, so switched to ginger teas and such like.

Anyway, there doesn't appear to be consensus on whether coffee/tea drinking in moderate amounts is good or bad, but I've seen more suggestions that it's beneficial than otherwise. Any input to that?