There's nothing stopping you from creating extra folders under /app to contain various types of service objects. Personally I have:

  /app/factories - for classes which create active record objects
  /app/services - for classes which do something I generally don't care about the return value of. Often perfect for background jobs.
  /app/decorators - most of these are Draper classes
  /app/forms - form objects

and a few others from various other gems.