How do you emphasize unformatted Chinese text? In English, one can write, "I am mad at you!" as "I AM MAD AT YOU!" for greater emphasis; on the internet, it's seen as "yelling". Absent the ability to format text (say, bold or italics), what is done / can be done to emphasize a statement in Chinese other than simply adding more exclamation marks or some kind of emoticon?
Emphasis mark (underneath dots) is the Chinese counterpart of italics. 

In printing, besides emphasis mark, fonts are used for distinguishing purposes. Bold (黑体) is also considered as a different font (rather than a variation of the same font).

In handwriting, people use straight underline and tilde underline.