What techniques have worked with putting your 3 year old to bed so they STAY in bed?

I have been trying for 3 months to get my 3 year old to stay in her bed at nighttime. She is constantly getting out of bed, coming out of her room, asking for water/milk/potty/songs/books/etc. Sometimes this lasts for an hour and a half and she has been known to throw things at her door in anger! We've tried the "super nanny" technique when we continuously put her back in her bed without saying a WORD to her for about 5 weeks now, but nothing has worked. Now I have a newborn baby to deal with at nighttime, which have made things difficult. What techniques have worked for you parents out there? I've heard of parents putting gates up so the kids have to stay in their rooms, and even locks on their doors. Help please!!