As people update MCP data into the Data Files area on Yahoo, those MCPs are added to this "master" database file maintained by Gary Hahn, so I think this may be one of the most "complete" collections of MCPs for North America. You can rename your existing atcsdb.mdb file in the installation directory (after closing the application), then replace with the one inside this .zip file. Download master.zip from this link:
http://finance.groups.yahoo.com/group/ATCS_Monitor/files/Data%20Files/zMaster%20Database/
If you're "just looking" then you might want to create a profile with an alternate database path (see the General tab in the options).
For those who provide updates to the Yahoo Data Files area, please check the box to notify the group as you upload. This is Gary's trigger to grab your latest files for import to the master.
This database is primarily intended to be a baseline for new users, or as a more or less definitive address lookup database in case new addresses are heard at a user's location. Decisions on what files to include, when there are conflicts, are strictly up to Gary's discretion and does not imply inferiority of other file sets.
BCP-only Master
Download BCP.mdb and import for 3.5.2 and above users. These are "MCP" entries for the BCPs that CSX uses, each containing a unique ID.
Layouts Master
No longer available. See the Yahoo group files area for current versions of layouts and MCP files.