This first question comes in a round about sort of way. My friend Tom mentioned my blog on his, with a question about all the symbols in the banner of this blog. So I figured I could at least explain that. Honestly, I was kind of surprised at the explanation for some.
From left to right:
Hindu "Om" - said to be the primordial sound that is said to represent God.
Jewish Star of David - It use as a symbol of Judaism began in the Middle Ages and it said to represent the shield of King David, though little proof of that can be found.
Buddhist Dharmachakra - literally means "the wheel of transformation" representing the eight-fold path of the Buddha
Christian cross - represents the method in which Jesus was killed.
Taoist Taijitu - illustrates the concept of yin and yang, that two opposing but complementary forces are found in all natural things.
Muslim Star and Crescent - While its association has little to do with Islamic theology, its use by the Ottoman empire has linked the star and crescent with Islam.