I love tattoos. They are seriously addictive. I think a cute idea for matching tattoos is initials or something? or a word/object that stands for something meaningful (like your halo idea is a good one). I know a friend of mine got TLC on her foot with her two best friends. TLC Tender Loving Care, but it also stands for Tristan, Lynna and Cora (her and her two friends). Make sure it's something meaningful that you will always remember WHY you got it and WHAT it means