Little Things: Refactoring with Hashes

  STUDENT_LEVELS = Hash.new(Student::Unregistered).merge(
    freshman:  Student::Underclassman,
    sophomore: Student::Underclassman,
    junior:    Student::Upperclassman,
    senior:    Student::Upperclassman,
    graduate:  Student::Graduate
  )

klass = STUDENT_LEVELS[params[:student_level]]
student = klass.new(name, birthdate, address, phone)

Source: Buckblog: Little Things: Refactoring with Hashes

A nice little pattern