Novel compounds, methods, and compositions for treating various viral infections are described. In some embodiments the novel compounds of the invention are 3-oxo-phenothiazine derivatives; more specific embodiments include 3-oxo-phenothiazine derivatives having substituents at the 1-, 7-, and 9-positions of the phenothiazine parent ring. In other embodiments, the invention provides compositions and methods for treating viral infections, especially HIV.