LAME compiles on Windows, DOS, GNU/Linux, MacOS X, *BSD, Solaris, HP-UX, Tru64 Unix, AIX, Irix, NeXTstep, SCO Unix, UnixWare, Ultrix, Plan 9, OpenVMS, MacOS Classic, BeOS, QNX, RiscOS, AmigaOS, OS/2, SkyOS, FreeMiNT(Atari) and probably a few more.
http://lame.sourceforge.net/download.php