Distributing VBA Modules or Macros to multiple Excel files

Is there a good way to distribute VBA code or a macro into multiple Excel files? We have a series of reports in Excel that have gotten out of hand. It started with a few and now we have a couple hundred variations. They want something written to automate some of the common functions in the reports and I have been struggling to find a way to get the code into each file without actually having to open each one and paste the code into it. Is there an easy way to accomplish this or is there a utility out there that will help with this? Hopefully there is an obvious answer and I am just not seeing it.