I found a number of directories for things like yellow pages and such. However, many were no longer being supported. Here is my overview.

• mXDirectory - v3.0.1 RC1
• efqDirectory - v0.1.8 alpha
• xDirectory - v1.5 (last updated 2004-09-24)

Some notable aspects worth sharing.

mXDirectory is supposedly an upgrade to xDirectory and has the ability to link to Yahoo Maps (at least until they change how that works). efqDirectory allows for multiple directories.