Maximal estimates for multi-sublinear operators are established which allow one to apply Nikishin's factorization theorem to obtain factorizations through weak-Lp spaces. Combining this with a result of Kalton's, any bilinear operator from a product of type 2 spaces into the space of measurable functions factors through a Banach space. Thus, every such operator can be viewed as a linear operator acting on the projective tensor product. Applications and related open questions will be discussed.