This add-in for VS.NET 2003 automatically:
  1) Registers the assembly in the GAC right after it has been built.
  2) Exports types to COM: produces the type library (and registers it if specified) .. as tlbexp.exe does.
  3) Registers classes in the registry ..as regasm.exe does.
  4) Avoids the bulding of an Assembly if its read-only attribute is set.
  5) If a build fails, it stops the build process for the remaining assembly in the solution.
You configure the Add-in behaviour for your VS.NET project by placing appropriate entries in the section of the project app.config file.

Note: if you use VS.NET 2003, read this tip to see how you can configure simple pre and post-build actions without the help external add-ins.