Caffeine is one of those gray areas for me. Coffee, I can't handle straight (and I know I'm not the only one) but good coffee is palatable with just cream, so it isn't paleo-horrible. And CR wise, it does have B vitamins and few calories, even with a little cream.
Tea, eh, I go through phases. Genmai-cha is one of the very few I drink consistently, and as April once pointed out on her fabulous blog, in a way it satisfies any residual or random grain craving you might have, since it tastes like what it is green tea + roasted rice.
Other sources of caffeine? I've come a looooooooooong way, baby. I have mostly cut out diet soda, and that would be my only other source. No, wait, I'm lying. I do eat chocolate. Diet soda would be my only other concentrated source.
The thing is, I don't think there's anything wrong with caffeine. It perks me up in the morning, but it doesn't give me a hardcore buzz, and it never has. It may be a genetic thing--my mom can drink a cup of coffee and fall asleep half an hour later, so can I. And I love, love, love a shot of espresso after a nice dinner.
But then I hear these tropes about how caffeine increases appetite, etc. So I go through caffeine fasts. I guess I'm just wondering if it's necessary? Some of the healthiest people I know, including bloggers like Mark Sisson and the aforementioned April, consume caffeine relatively regularly.
Hmmmm, on the fence about this once (while clutching my morning coffee in one hand...)