Mikmod is a module player and library supporting many formats, including mod, s3m, it, and xm. Originally a player for MS-DOS, MikMod has been ported to other platforms, such as Unix, Macintosh, BeOS, and Java(!!)
FreeMAX is a M.A.X.: Mechanized Assault & Exploration mod that allows you to play M.A.X. with the Stratagus engine, as opposed to play it with the original M.A.X. one. So you need to have a legal copy of M.A.X.(original DOS Version required).