On: How Did Vim Become So Popular?

[Lio]

Map caps to ctrl and you can get access to a world of convenient insert mode shortcuts.

ctrl-[ (for right hand) or ctr-3 (left hand, thanks teddyh) => escape

ctrl-i => tab

ctrl-h => backspace

ctrl-m => return

ctrl-w => delete prev word

ctrl-u => clear line

ctrl-o => cmd mode for 1 cmd

...and many, many more, including all the completion options.