The Custom Property Propagator provides an efficient means of managing Custom Properties across multiple SolidWorks files.  It allows you to define all your properties in one place and then propagate some or all of them to whatever groups of SolidWorks files you like. The properties you define won’t disappear when you exit the program or finish running a batch of files through. They’ll stay there until you decide to delete them. If you don’t want to use some of them on a particular run, just uncheck them and they will be duly ignored. You can choose to delete or overwrite undesired properties, or you can leave them alone.  Now in Version 3 you can also save off each set of properties to retrieve whenever appropriate for the type of files you're working with.

You don’t even have to enter the properties into the Propa-Gator if you have a sample file that has everything the way you want it. With a simple click, the Propa-Gator will replicate all the properties from the sample file and enter them for you to accept or edit. And the Propa-Gator is FAST! If you are dealing with properties at the Model-Level, the program does not need to open the files in SolidWorks, but simply writes your properties and values directly.

How Does it Work?  Take a peek at the Custom Property Propa-Gator Instructions. 
Also, check out a Fantastic Podcast Demo created by Ben Eadie of Mountain-Wave !

If you want to try it out, the Light Version is FREE! Of course, I would like to encourage you to upgrade to the full version, going for the bargain price of only $49.

Take a look at all the included features!

• Do Find & Replace searches on all the properties in all your files
• Search on Property Names, Values, or Partial Strings
• Change Density, Color, and Optical properties in your part files
• Propagate “smart” Mass Properties that update appropriately for each file
• Bulk changing of Drawing Templates
• Propagating Material Properties
• Propagating Summary Info  

Current Version is  Version 3