Not just in an internet setting. I used semicolons many times in most of my senior papers. My teacher was impressed mostly because some of the other brain-dead slackers in my class might not even know what a semicolon is.

Semicolons, colons, and even the common comma when used in less intelligent posts, all make the user feel smarter. The same way CAPS seem like you are yelling and txt talk seems like your 7 years old and 1337 makes you look like you speak gibberish.