Microsoft is famous (or should I say, infamous) for
barraging interviewees with a slew of impossible questions. Such has therefore unsurprisingly happended to
one of our usergroup members during a phone interview.
Of particular interest was the riddle listed as point #5 by my UG mate:
Brain Teaser: You are in a room. You have 1 question to ask and need to know the way to heaven. There are 2 doors. A door to heaven and a door to hell. There are 2 people in the room. One will tell you the right door to heaven (if you ask where is heaven?) and one will always tell lie. 

If you wish to solve this yourself,
do not read the segment below.
I don't have the "model answer" but here's my take: I'd ask any one, "
could you ask the other person where s/he thinks the door to heaven is?", and then pick the door opposite the answer.
By asking so, I involve the liar scum either way, which will result with an inverse answer:
 If I ask the honest person, he will ask the liar where the door to heaven is, which the liar will reply falsely. The honest person will tell me exactly what the liar said.
 If I ask the liar instead, Mr Honesty will give the correct answer but he won't happy with me knock knock knocking on Heaven's door. So the stinking blighter will twist the truthful answer into falsehood anyway.