Oprah Winfrey is investing in Dr. Barbara Sturm's skincare line. In an interview available on OprahDaily.com, Winfrey said she tried the products, loved them, called Sturm and said she wanted to invest.  “I have never done that before. Ever,” said Winfrey. “So that's how good the products are.” Among Winfrey's favorites are Enzyme Cleanser and Glow Drops. She also likes the Darker Skin Tones Collection. No word, however, on exactly the size of Winf...