I kept mine simple like myself lol. St georges cross ( im a patriotic dude ), a smiley face, 77 ( year i was born ) and two crossbows ( my favorite weapon ). Every so often you see a really good one i saw family guys stewie the other day holding a ray gun that looked good.
As someone with good memories of final fantasy when I was younger, I put effort into making a few FF-based emblems. Right now I got Cloud from FF7, Vivi from FF9 and Tifa (also FF7) is in the making, still perfecting it though.