Following up on Jesse Walker's Halloween-themed links, I'd like to commit a public service by linking to Snopes.com's authoritative debunking of the myth of poisoned Halloween candy (for those unfamiliar with it, Snopes explores the veracity of urban legends). A snippet:
It's a sadness that a holiday so thoroughly and greedily enjoyed by kids is being sanitized out of existence in the name of safety. Sadder still is there appears to be little reason for it.
Though I've yet to find evidence of a genuine Halloween poisoning, I have uncovered a few isolated incidents initially reported as random poisonings that, upon further investigation, turned out to be something else.
That something typically turns out to be a gruesome intra-family homicide or the mad ravings of a Jack T. Chick comic-book religious tract.
Whole thing here. More Snopes on Halloween urban myths here (including info on pins, needles, and razor blades in Halloween treats–something that does actually happen from time to time, though typically as a hoax).
True tale of Halloween killjoy here.