Magnon-assisted transport across a tunnel junction between a ferromagnet and a normal (nonmagnetic) metal is studied theoretically. A finite temperature difference across the junction produces a nonequilibrium magnetization that drives a charge current, mediated by electrons via electron-magnon interactions, from the ferromagnet into the normal metal. The corresponding thermopower coefficient is large, Ssimilar to-(k(B)/e)(k(B)T/omega(M))P-3/2(Pi(+),Pi(-),Pi(N)) where P(Pi(+),Pi(-),Pi(N)), 0less than or equal toPless than or equal to1, represents the degree of spin polarization of the current response to a bias voltage, and depends on the relative sizes of the majority Pi(+) and the minority Pi(-) band Fermi surface in the ferromagnet and in the normal metal, Pi(N).