MacVim
Vim, the text editor, for Mac OS X
...All commands are given with normal keyboard characters, so those who can type with ten fingers can work very fast. Additionally, function keys can be defined by the user, and the mouse can be used. Vim runs under Amiga DOS, MS-DOS, MS-Windows (95, 98, Me, NT, 2000, XP, Vista, 7), Atari MiNT, Macintosh, BeOS, VMS, RISC OS, OS/2 and almost all flavours of UNIX. Porting to other systems should not be very difficult. There are separate distributions for Unix, PC, Amiga and some other systems.