As Keith and Chris note - a darker (as in the darkest you can get) roast and boiling water is going to lead to a (in time, with experimentation, pleasant) over-extraction. Something else you can do is add a pinch of sea / kosher salt to the grinds prior to pouring in the water.
This will not make your coffee salty, it will simply bring out the natural bitterness of the extra compounds the over-extraction will produce. You can use a pinch of salt if you want to back off the temperature of the water, or how dark the roast is, in order to achieve basically the same effect as you would with either.
You have to experiment a bit, I use this method to get a more bitter / robust medium-roast Arabica quite frequently.
Also works wonders in drip coffee filters.