We've open sourced:

• app_extension_generator

  Generate plugins with migrations, an app directory, routing extensions, test, and lots of jazz. Like mini rails apps.

• Lightning Test

  Testing plugin that uses blocks to check that ActiveRecord records are created as expected.

• liquid_db_views

  A Rails plugin that renders liquid templates out of a database. For more information about the liquid template language see http://www.liquidmarkup.org/

• Unique Tuple

  An ActiveRecord migration for validating uniqueness of a set of columns.