I have created and uploaded the source code for a simple application that combines OPML files together. This is a simple application that takes n number of file or url paths to opml files, and then writes a new opml file to standard out that contains all of the unique outline entries from all of the specified opml files.
The application is written in C#. Only the source code is provided.
Usage : CombineOpml opmlPath1 opmlPath2 ... opmlPathn
Example, the following outputs a new opml files containing all of the unique entries from two online aggregators and then saves it to a file named combined.opml
CombineOpml http://www.markme.com/mxna/opml.cfm?category=Flash http://www.fullasagoog.com/opml/FlashMX.opml > combined.opml
Use at your own risk.
The app is free, but if you end up using it, send me a postcard.
You can download the source code from here.