Give them code to write (Score 1)

I am a senior software specialist for a large data center and I frequently interview programmers for open positions. The MOST effective question we have found (weighted 50% of the interview) is to give them a coding problem. For intermediate programmers we ask them to parse a word out of a string (that we give them) in any language they know. They are asked to write their CODE on the white board. Actually, we give them the question prior to the interview and give them 30 minutes to think about it.