I don't know if you're familiar with grammarist.com but it's a great site that answers many nit-picky questions about spelling and grammar, covering the proper usages/spellings for all English language countries.
Anyway, a debate started between my father and I over "canceled" or "cancelled" and I ended up on the Grammarist, where I found the comment below:
"Thank you! Our posts tend to gradually accumulate comments over months and years, and this one is still sort of new. Also, it's not controversial at all. If you want to see lots of comments, see "Gray vs. grey" and "Spelled vs. spelt" (both always in the "Most popular today" box up there in the sidebar to the right). They get kind of ugly, though. We gave up trying to police them long ago."
Nothing makes me happier than seeing mods on a grammar site talk about the out-of-control fights that happen in the comments on articles about grammar.
The world is a beautiful place.
The exact page that quote came from can be found here.
ETA: the canceled/cancelled debate answer is: the single L is correct in the US while the double L is correct in other English-speaking countries. Cancellation is correct for both. More explanation is provided at the last link.