For years I have been reading about vinegar as a natural cleaning solution but have always hesitated.  My hesitation was that it will not be strong enough to cut through any grease or grime.  I picked up this tip from my Aunt who is well into her 80's and has never purchased a cleaning solution her whole life.  She has always used natural and organic solutions.  The trick with cleaning a microwave....you mix 2 cups of water and 1 cup of vinegar into a microwave safe bowl, uncovered  and turn on the microwave on for 4 minutes.  What happens is the solution steams the micovwave clean and leaves and unbelieveable shine.  After years of basic use, microwaves generally get a greasey film or a build up of sorts.  Once the microwave buzzed she waited another minute or so then opened the door - let me tell you the steam that came out of the microwave was very apparent !!  She then took a clean cloth and simply wiped out the entire microwave - what a shine and then I gently ran my fingers on the interior and no greasey film.  She further took the boiling solution and poured it down the bathroom sink - she let me know that it helps break up hair and build up in your plumbing pipes.  There is something to be said about age and wisdom!  Great Reduce, Reuse & Recycle cleaning solution!