heck yeah, this is eXACTLY the way I like to spend my evening!! Here're the Crow Summer dudes…
Nina just has your garden-variety selfie. She's smiley and cheery, it probably has a little bit of a filter on it. It either has her dog or her sheep in it with her. She changes it every couple of months.

.
Reese has Alphonse Elric because his best friend back in Oregon reeeeeaaaallly wanted them to have matching anime avatars. Reese was 100% not ok with being one half of a yaoi couple and so put his foot down and refused to be anything or anyone other than Alphonse Elric. He changes it every now and then to a different Alphonse, but he doesn't really worry about it a lot.

.
Mordecai has some M.C. Escher picture or other optical illusion because he was crazy obsessed with them when he was like 15 and he never changed his avatar and now optical illusions are his brand.

.
Dietrich has the default profile feller, but he added a smiley face as a joke after someone (READ: Nina) complained that it was too emotionally detached and cold.
.
Juliette has this picture. No context. Just this picture of two knives.

BONUS:
Reese's mom has that one really famous pic of Beethoven where he looks like he's about to stab you with his pen.
Bernard has the typical dude selfie where he's smiling without his teeth showing and the lighting is kinda grainy. He changes it every couple of weeks but it doesn't matter because he always looks exactly the same.
Frenchy French (aka the blue-haired girl) cycles out new duckface selfies every few weeks. Some of them have Bernard in them making his typical expression.
Ruthie has a 110% flawless photo of herself looking totally beautiful and badass as she's about to sky-dive out of an airplane.