We're going to run the coffees off against one another as there is a difference in the amount of caffeine found, depending on how fresh the beans are and how they are processed. As a rule of thumb, beans you grind yourself are the most potent, and the instant powder stuff is the least potent. That said, it still packs a wallop that'll leave you in lala land if you over compensate and drink two mugs a minute.

Reaction Times

Results

Upon waking up: All: Sluggish Snail
After drinking: All: Ambling Armadillo
15 minutes after drinking: Bean: Rocketing Rabbit, Ground: Bobbing Bobcat, Instant: Bobbing Bobcat
30 minutes after drinking: Bean: Bobbing Bobcat, Ground: Ambling Armadillo, Instant: Ambling Armadillo
An hour after drinking: All: Ambling Armadillo

The Buzz

The buzz provided by coffee of all types is tempered by the way in which you drink it. Coffee is generally drunk over a more spaced out period than say, Red Bull, and so the effects are more gradual and measured.

It wakes you up and focuses you without making you excessively hyper or focused. (Unless of course you're like a friend of mine, who once went through 11 cups of the stuff in 15 minutes. He was neither calm nor measured afterwards...)

The difference between the coffees is, to the untrained and scientific observer, negligible as far as buzz goes... taste perhaps, but not the buzz.

The Crash

As the drinking of coffee tends to be spaced out over time, one never really feels the stuff wearing off while drinking, unless one goes for a good while between cups. However, after a sustained few hours of coffee drinking, the cumulative effects will make your body a temporary addict that rivals that of a hardened druggie. Cold turkey in the evening can lead to a violent reaction combining headaches and shaking among other symptoms.

Some people just continue to drink coffee or other caffeinated drinks in the evenings, albeit in lesser amounts, in order to satisfy the urge to do so without fulfilling any particular need for concentration. When this happens you're officially an addict.

The Other Stuff

Anyone here ever heard of caffeinism? Well err, before you begin to rely on this stuff I'd suggest you read up on it and take note before you down twenty cups a day.