I have always been frustrated by the lack of consensus on how to emphasize flat text.
Is it:
I am NOT gonna take it anymore?
or
I am *not* gonna take it anymore?
or
I am _not_ gonna take it anymore?
Caps kinda work in the example above, because I'm shouting.
They not so good when you're just being emphatic, as in:
Crossing by covered wagon took six months. Today, we can fly across in six HOURS.
What do you use?