The Solar Cross, also called the Wheel Cross, is one of the most basic symbols known to man and appears in one form or another in almost every culture. Though some civilizations do however have stronger ties to this symbol than others.
The Celts viewed the Solar Cross as a symbol of Draíocht, or druidism. It is said to have represented the Celtic concept of the year with the holy days of Imbolc, Beltane, Lughnasa and Samhain as the bars.
The Asatru, or Norse reconstructions, associate this cross with their principal deity Odin. Though this connection is often sited I am unable to find historical data to confirm this, so it could well be a modern but very prevalent belief.
Many indigenous North American people view this as the medicine wheel. It has come to represent a native way of life and a symbol of native pride across several Nations.
As a sad note like many symbols used in early Germanic traditions the solar cross has been hijacked by hate mongers. It has been used as a symbol of white supremacy in the States. It should also be noted that several people, myself included, wear this symbol as a expression of religious belief and cultural pride, and in no way support the goals, actions, or beliefs of bigots. In fact, this symbol is most commonly seen as a part of the Celtic Cross, a symbol of cultural and religious significance for the people of Ireland and their descendants.