Found on my current favourite blog, Passive Aggressive Notes, this example of a comma splice altering the meaning of a sentence is a lesson to all who use commas like confetti.

Thanks to those who used this as a trash can, you have no soul.This is worse than your average splice as the comma unintentionally turns the phrase, ‘you have no soul’ into a subordinating clause. In other words – because of the people who use the bin for rubbish, the reader of the sign has no soul. I like to imagine a particularly forlorn student (possibly listening to My Chemical Romance or the Smiths) wandering past this notice and thinking, “So that’s it; I knew someone was to blame.”

Brilliantly, a passing zealot spotted this error and resolved it with an act of grammar vigilantism.