Google directory has been retired some time ago, and now replaced by Google Places or for more specific is Google Places for Business, you can claim your business listing on Google for free of charge.
In addition to Google's directory there are also other directories that you can consider such as DMoz, Yahoo Directory, or even our SEOzoic business directory. Here is a brief comparison of the three directories:
Directory is one right way to improve your online visibility, but choose it wisely.