Lots of people have a special reason to get an angel tattoo: as a symbol of a loved one who has moved on to a far far better place than creepy smelly planet earth (it's one of God's earlier works, really he's done much better in far trendier parts of the universe, where the angels hang out, by the way.)
Angels are sometimes depicted as protectors of souls and are sent to earth to point stupid humans in the right direction, punish transgressors or collect souls (as per the angel of death, aka grim reaper).
Lucifer is a well known bad-ass angel, got all up in God's grill because he thought he'd been dissed. Long story short: Lucifer got a smack down and was put in charge of earth.
