Siddhis or Supra-normal abilities are by-products of concentration and/or spiritual development. It is an oft repeated maxim that they (Siddhis) should not be intentionally cultivated if one is serious about their spiritual advancement. Since spending time on development/perfecting of any Siddhi(s) is like taking a (complete) detour from the spiritual path either for cheap material gains or mockery. Perfect Masters or Siddhas manifest Siddhis for benefit of others (like healing etc..) and never for any commercial gain.
It does not harm however to know that there are people who either naturally or intentionally have such abilities. Here is one book that I found online, that has example of Real people and their abilities cataloged by Vincent J. Daczynski. A story of special mention is that of Charles F. Lutes (chapter 11 in the book), who became a Jivan Mukta (liberated being) after coming into close proximity with Maharshi Mahesh Yogi. He worked closely with the Maharshi in teaching Transcendental Meditation and had healed several hundreds of people. You will find the book here –
Amazing Abilities
Kathanand Swamigal 