Wow, you guys are all kinds of devious, aren't you? *grins* I'll have plenty of good traps for our heroes come Saturday.
As for killing off main characters--it's happened to our party, but not frequently. There've been a couple of times when I'm pretty sure one or two of us should've kicked the proverbial bucket, but our DM tends toward mercy. It all depends on who you've got playing, really--we've got a fairly mature group for the most part, so we usually go with adventures that are challenging but survivable. Playing with younger kids, I'd definitely keep main characters alive. And, after all, it is supposed to be fun. When people start taking it all hyperseriously, it's no longer fun, at least for me.