One of those annoying poses that's English name is just as hard to remember as it's Sanskrit. Marichyasana I or Pose Dedicated to the Sage Marichi A. Ha!
I love love love love love this pose. It appears in the Primary Series of Ashtanga. Super great twist, shoulder opener, hamstring lengthener, quad strengthener, and core work. Bandha yoga emphasizes the importance of engaging the quadriceps:
There are a lot of hurdles to achieve a deep forward fold in this pose. Tight shoulders + hamstrings, or weak adductors. My one big tip: strongly stamp the foot that is closest to you into the floor...as if you were about to stand on it. That will bring more power into the upper body to fold forward.