There are many. Look up any of the following and there will be some evidence. Tyrosine; precursor to dopamine, magnesium and b6, which are needed for the conversion. Tyrosine rich foods. Apple cyder vinegar,alkalising the body.  Omega 3, epa and dha. Other things which have been found to increase dopamine are exercise and music. Correcting deficiencies especially zinc, iron, vitamin d, protein and digestive enzymes. Testing for food intolerances, particularly wheat and dairy then avoiding or minimising them if necessary. Meditation. Having info to hand to avoid forgetting what to do.Specific physical exercises if didn’t crawl long enough as as baby to break the tonic neck reflex. Coffee. Coaching. I reckon try and do as many as possible and see what happens!

I know for my husband, the simple stuff seems to work the best. Exercise, sleep, good food. I think what fijay has to say is very valid; great vitamin information in there that could really help anyone, not just folks with ADHD.

Also, medical professionals agree with fijay and myself:

Alternative ADHD Treatment: Nutrition, Protein, Fish Oil, Diet ...

Exercise: An Alternative ADHD Treatment Without Side Effects ...

Alternative ADHD Treatment: Natural Remedies and ‘Green Time ...

Positive Behavior Support is always a great route to take.

Coffee has seemed to help me in many ways with ADHD

Yes, i am currently seeing a Naturopath who has found me to be Zinc & Vitamin B6 Deficent, i am currently taking these plus magnesium and 5-HTP (5 hYdroxytryptophan ) for depression. The supplements that are to directly help with my ADD include Tyrosine & Phenylanaline and some other liquid potion that the naturopath creates herself. I am still on max. dose stimulants as have only just started taking these supplements and apart from the eased depression symptoms have noticed no difference with the ADHD symptoms, early days yet though! once i build a foundation with all the dopamine boosting supplements i will begin to ease off the stimulants. I am also having tests to determine if my gut bacteria/digestive enzymes is healthy as apparently this relates very much to ADHD. I will then embark on a genetic test to find out if i have the gene that causes distortions in metabolizing Zinc & Vitamin B6. Then as a final stage, i will look at Neurotherapy or Neurofeedback which is a Brain Mapping/training tool administered by a trained neuro-psychologist. i am also trying meditation, trying to practice on a daily basis to get the most benefits. I have always used Exercise to help with my ADHD/Depression, it it what has kept me from going insane all these years!! i therefore Highly recommend regular aerobic exercise and spiritual meditation. With regards to the Tyrosine & Dopamine issue, i HIGHLY RECOMMEND people struggling with ADHD, Depression or Anxiety read ‘The Edge Effect’ by Eric Braverman. Some excellent info in there on how we can alter our own Brain Chemistry. If there is anyone out there who has successfully come off stimulants or found a non-drug treatment for their ADHD, I would LOVE to hear from you!! please email me @ .(JavaScript must be enabled to view this email address)

Interactive Metronome has been proven to be very effective. 

In an ADHD study - A double blinded placebo controlled study of 9-12 year old boys diagnosed with ADHD found those who completed the IM program showed significant improvement in attention, coordination, control of aggression & impulsivity, reading and language processing.  This study was published in the American Journal of Occupational Therapy, March 2007.

Go to http://www.Afocusedbrain.com to read case studies and see video news stories of this treatment.  It is 100% Drug Free.

I found a place on Craigslist that does Cognitive Brain Training, Learning Rx, and enrolled my son in the program.  We had tried meds for a while, but didn’t like the zombie that came with it.  Having 3 people in the house with ADHD is pretty hard, but this brain re-training seems to be working for my 10 y/o son.  Will look at enrolling oldest (20 y/o) and possibly husband.  We are also all doing the elimination diet, and going to a play therapist.

We have put my 8-year-old son with ADHD through two sessions at a Brain Balance Achievement Center and it has helped him tremendously.  So far we have been able to avoid medications through the sessions and continuing the program at home. 

http://www.brainbalancecenters.com/

We are using Neurofeedback therapy, Craniosacral Therapy as well as Chiropractic.  All have been very helpful. We have not taken our son completely off of medications)however we have been able to eliminate at least one since we included the aforementioned alternative medicines.

The seated yoga and relaxed / concentrations developed by biofeedback specialist and researcher Jason Mark Alster MS have been proven to work. try the video, Being In Control: Natural Solutions for ADHd Dyslexia and Test Anxiety.
http://www.amazon.com/dp/B004RENW3C

We have been doing the Handle method with great results for about 9 months and we are nearly finished with it. It seems to have helped tremendously. We have also added omega 3’s and vitamin d, after seeing Dr S. Newmark at UCSF.
Everything seems to be helping, and we are in a way better place than we were a year ago. That said, I don’t feel like our journey is complete- perhaps we are 70% improved.