Firebug Elise. Elise's Abdomen is lit like a bulb of a firefly, as well as her spiders', she would be generally brighter than her normal skin (ex: spectral and spooky skins). A warmer tinge to her normal skin. No other special changes. (Her human form would reflect skin colours)
Gypsy Elise. Haven't got far through this one, but its something I think would be fun to play with. It's based around her Abdomen being a crystal ball.
Basketball Syndra. Orange and white Jersey with 1 on back and front, short white skirt like her current black on, sweat band over her head and eyes. faint basketballs (and since they get empowered orange, its pre'y awesome, hey? xD)
Prospector Gangplank. Blue raggy overalls with a white longsleeve top underneath, raggy long trim hat, normal knife and an ol' western gun.
Colonial Karma. Croset and tight fitted gown, plain white ''air fan'' (with dagger attatchments, naturally), hair in a bun like Sakura and Sun Goddess, with small powdered white wig.
Clown Trundle. Balloon animal (ballon) weapon, big red nose, afro, big floppy red shoes and ragged colourful clothes.
Bridal Karthus. Wedding dress robes with black and dark navy detail (reverse karthus? :P) instead of a chapeau a bridal veil pushed back, wilted flower bunch as his scepter, and a book as his... book.
I would love if anyone could help with some concept art for any of these skins that they like, I will try and get my own done, but I'm a bit of a shoddy artist. Currently lacking in the pencil department at the moment, haha.