If you use a Mac/OSX, then enter the following commands in your shell and reboot:
$ defaults write -g KeyRepeat -int 0 $ defaults write -g InitialKeyRepeat -int 15
If you live in a text editor or the shell, or otherwise spend most of your typing hammering away at the keyboard like I do, then this makes an absolutely wonderful difference in the responsiveness of any typing activity. It will make your previous typing feel like you were pecking away in slow motion at the bottom of a pit of cold tar!
Yes, I know you can set the keyboard repeat rate in `System Preferences`.
I, too, did that a long time ago.
But this trick takes the speed to a 11 ...