The triskele, or triple spiral, a symbol closely related to the triquetra, is a tripartite symbol composed of three interlocked spirals. The spiral is an ancient Celtic symbol related to the sun, afterlife and reincarnation. The example above comes from the Neolithic "tomb" at Newgrange, where it is supposed by some to be a symbol of pregnancy (the sun describes a spiral in its movements every three months; a triple spiral represents nine months), an idea reinforced by the womb like nature of the structure. The symbol also suggests reincarnation- it is drawn in one continuous line, suggesting a continuous movement of time.
Triskeles are one of the most common elements of Celtic art; they are found in a variety of styles in both ancient and modern Celtic art, especially in relation to depictions of the Mother Goddess. They also evoke the Celtic concept of the domains of material existence- earth, water, and sky, and their interrelations.
I think it would make a really good tattoo!