Yeah, I'm still trying to figure out when to use a full colon and when to use a semicolon. I think semicolons are really cool; yeah... I know I'm weird.
Hard and fast rule on semicolons:
He is a cad, a bounder, and a boor.
He is a cad; he is a bounder and a boor.
He is: a cad, and a shameless cad at that; a bounder, and a bounding bounder at that; and a boor, and a boorish boor at that.
So you can use it either as a more-emphatic comma or a less-emphatic period. Kurt Vonnegut says that they are pretentious and shouldn't be used. Kurt can go @#$% himself. I think they're fantastic at filling the space between commas and periods.
I'm a writer (as in, novelist), so I generally use punctuation and grammar based on how it makes me feel -- even if it's a comma splice or some other mutation that wouldn't be acceptable in a formal essay. And as you might have noticed, I'm deeply enamoured of the "--", the ellipsis, and colons and semicolons. I also use "more" when my mother (an English teacher) says I should use "most" -- for instance, "She was among the more buxom of the girls on my block." Since I'm comparing at least three girls, my mom says I should use "most," but I view it as comparing two groups of girls -- the more buxom and the less buxom. So this girl's boobs are in the top half, roughly, but not in the top 10%.
So anyway, I'm not a prescriptivist. I just want people to make friggin' sense. If I can understand what you're saying well enough to correct you, then I won't say anything. If I can't even understand you that well, that's when I get angry.
