Some bits and pieces on her from around the web:
Old but ahead-of-the-curve Bloomberg profile, from June 2010, when Lagarde was still finance minister of France. NB that one of the authors, Lisa Kassenaar, is now Bloomberg's Global Editor-at-Large for women's coverage.
The New York Times profile from just after her appointment to head the IMF, "Mme. Lagarde Goes to Washington."
A blog post by my friend Ken about her call this past August for European banks to raise capital. Prescient call on her part, prescient of Ken to notice that she is a terribly smart cookie.