Although the Mozart Effect research was based around one piece many believe that all classical music could have the same properties as well. Some research concluded that in order to receive the mental benefits the listener should enjoy or have an emotional response to the music. This is a sample collection of some of Mozart's famous compositions. They can be purchased at Music44.

Symphony No.40 In G Minor, K.550 - Buy Now  Play Sample
  The “Great” G minor symphony. Unquestionably one of Mozart's most greatly admired works.
Piano Concerto In C No. 21, K.467 - Buy Now  Play Sample
  Known as being played in the movies: Elvira Madigan and The Spy Who Loved Me.
Piano Concerto In C No. 24, K.491 - Buy Now

  Symphony No.40
  In G Minor, K.550

  Piano Concerto In   C No. 21, K.467

  Piano Concerto in   C No. 24, K.491

  Violin Concerto in   D No. 4, K.218

  More Mozart
  Powerful and emotional. It is considered to be the most played of all the concertos.
Violin Concerto In D No. 4, K.218 - Buy Now
  The second movement of this concerto is also very popular and easily recognizable. The violin's
  melodies are deeply lush and beautiful.

Symphony No. 29 - Buy Now  Play Sample
  The First Movement in this symphony is the most well-known. The exuberance and cheerful tone
  of the entire piece makes it a delight to listen to.

Piano Sonata No. 15 In C, K.545 - Buy Now  Play Sample
  "Sonata facile". A work that scarcely a student of the instrument fails to learn at some point in his
   or her career.

There are many different websites that contain valuable information about this phenomenon. Here is a few of them.

The Powers of Music: A Treatment for Epilepsy?
  This article discusses listening to Mozart can reduce seizures.
Music: Shaping Our Children's Lives
  This is a PDF file that describes how listening to music can shape everyone's lives.
Piano and Computer Training Boost Student Math Achievement
  A study on how music training can help Math scores.
Music and Cognitive Achievement in Children
  How child development can be affected by music.