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