I use the following regexes with [iTerm2][iterm]'s ['trigger' feature][it1] to create some basic syntax highlighting.
(?<=- )([A-Z][A-Z ]+:)+
Colorize CONSTANTS
Magenta
(?<=- )(:|")\w*"?(?= =>)
Colorize :keys =>
/ "keys" =>
Yellow
^([^=]*)(?==)
Colorize ENV_VARS
Cyan
(?<=[^=])=
Colorize the =
separator Dark Grey