I've seen a lot of questions on stackoverflow that will have what is basically the same correct answer all posted within minutes of each other. Example: Date / Timestamp to record when a record was added to the table?. The reason why this happens is the answer is OBVIOUS, and the questioner could have found the answer by doing 10 seconds of googling. It seems to me these questions simply clutter up stackoverflow and add little if any value. I think it would be useful if the system automatically flagged questions that had more than X# of answers in Y# of minutes for moderator review. A moderator could then mark the answer as "does not show sufficient research effort."
I'm going to agree with Pekka on this one - if the quality of the question is bad, then downvote, comment, and vote/flag to close.
There doesn't need to be anything extra in the system to point out that this question is obvious (and I personally feel that someone saying "LMGTFY" is a bit rude and means someone is trying to attack them personally). We have the ability to express our views on the quality of the post by voting and commenting (and for 3K+, voting to close).