Hello all, for those of you that do not know, I am a Quaker - aka the Religious Society of Friends.
The main emphasis of the Quaker theology is that each person is capable of knowing God and has that of God within them - the inner light.
The theology has a number of major testimonies:
Simplicity - you know that whole of idea of living simply so that others may simply live. One struggles with this all the time.
Pacifism - though not from a moral or political point of view, but a spiritual one. There is that of God within everyone and therefore to kill anyone for any reason is killing that of God within them. The Quaker pacifism is one about the fundamental reverence for life.
Truthfulness - being honest and not lieing and not misleading people into believing something that is not true. This makes you think about what you say and how you say it and even what you do not say. The reason Quakers do not swear oaths is that the swear an oath presumes that otherwise you are likely to be lieing.
Equality - all people everywhere at all times are equal. This is both in the spiritual and temporal realms. No Lords, no priests, etc.... It also means that Quakers do not use titles like King, Queen, Mr, Mrs or Dr. The titles evoke classes and that means no equality.
There have been more than a fair share of very influencial Quakers over the last several hundred years. The Quakers founded Pennsylvannia. Elizabeth Fry was a Quaker, but then so was Richard Nixon.
One the the reasons Quakers are often well known is that the Religous Society of Friends has an implicit call to action. Quakerism is full of activists that work hard each every day to make the world a better place.
The Quaker tradition I am part of is the unprogrammed meeting. We come together as a group and sit down quietly and wait on God to inspire us to speak. If no feels inspired, then no one speaks and we all sit in silence. When everything is insync, this is the most powerful religious experience I have ever seen, when not, you think about taking out the garbage or fall asleep.
For more informaiton, there is Canadian Yearly Meeting