Right Help, Right Mode

Vim's help system is incredibly comprehensive and dare I say, "kick ass". One thing that initially frustrated me though was that searching for a keystroke (i.e., :help ctrl-p) would always return the documentation for normal mode. You can search help for any mode by prepending an identifier to your query (:help i_ctrl-p) would display documentation for ctrl-p from insert mode. (:help v_ctrl-c) would explain ctrl-c from visual mode. Also, remember you can tab-complete help to make finding the right document easier.