Aside from being a whole lot of fun, the diabolo has many physical, social and academic benefits.

Physical Benefits of Diabolo and Juggling increases:

Outdoor activity
Rhythm and timing
Eye/hand coordination
Balance
Reflexes
Flexibility
Ambidexterity
Body orientation

Educational Benefits of Diabolo and Juggling by use both sides of the brain at once aids in:

Concentration
Problem solving
Imagination and creativity
Mathematic skills
Physics
Performance and drama
Technics in learning
is helpful with Dyslexia

Social Benefits of Diabolo and juggling:

Teamwork
Patience
Self Expression
Persistence
Communication
Self Esteem
Confidence
Encourages helping others