More modern crucifixes today involve Irish knotwork designs on them, which signify different meanings such as unending love, etc. The idea is that there is no beginning or end to these knots. Another one that you have probably come across is the Trinity knot, which obviously signifies the Father, Son and Holy Spirit intertwined as one God. Some of the other crucifixes that are often more difficult to come by involve pictogram designs which resemble the High Crosses found in Ireland. From what I remember, these pictograms were the primary method that the Celts told stories about the Gospels ( by carving men carrying Jesus away when he was arrested, etc.) because people were illiterate. The one I wear is a replica of the Cross of the Scriptures that was in Clonmacnoise, Ireland.