Namaste,
There are many rituals we can do as a group (ie: group healing amongst Reiki Cafe members on any given day), which I feel, raises the healing vibrational level tenfold when done as a group. This is not to say that individual meditations for world healing/peace are not as effective - because I believe that they are. As we are all connected as one, every little bit that we do gets connected to others who do their part all over the world, at any given time.
I have recently read about the World Peace Crystal Grids, both at the North and South Poles, placed by William Rand I believe. You can find further info on these grids through any search engine (I'm avoiding sending links as per Reiki Cafe post guidelines).
I have been introduced to the Antahkarana Tibetan Symbols, which can be used along with a Crystal Grid, charged with Reiki energy. It is said that these grids should be charged daily, or at least every 48 hours. In doing so, I believe, one can connect with the healing energies of the World Peace Grids at the North and South Poles. Personally, I find this a very powerful way of combining the energy of crystals along with Reiki, and any other guide you connect with.
There are more and more people going through a spiritual awakening, thus adding more and more collective energy to world peace/healing. If we all do our bit to offer healing and peace - to family, friends, strangers, this in itself can spread like a domino effect, thus reaching the ends of the earth.
Thank you for a much needed question/post!
Light, Love, and Angelic Blessings
Chakra_Rei