I went through this phase back in 2004 where I became obsessed with finding one-sleeve tops (I wasn't really into dresses then, I guess -- more separates). See, I have this huge scar on my left arm that's a relic of burning myself with hot water as a child. Had plastic surgery and the whole bit and now it looks like a shark bite, so it's pretty cool -- when I used to work with kids during my college summers, I'd tell them if they were naughty I'd toss them into a shark tank and I'd show them my arm. Ha, evil, I know.
Anyway, I'm kind of intrigued by all the one-arm wonders on the racks this fall. Margiela up top and Roksanda Illincic below.