Entity reference field in a block
Something along the lines of Bean or Boxes would probably be your best options (assuming one of the many Node in block modules aren't good enough).

I've got more experience with Bean, so I'll give a general idea based on that.

Both modules allow blocks to be created as fieldable entities.  You should simply be able to add an entity reference field as one of the fields on your block and set it up to display in exactly the same way as you currently do with your node/entity reference combo.

Looking through the issue queue, these modules may merge at some point, but I couldn't see anything that says which one is better.  My personal preference is Bean.