There's something about a girl who can pull of a good jacket. Especially a leather jacket. For some reason I'm rather nonplussed about leather jackets for guys. I don't mind them. But on girls, I co-sign for sure. I knew a girl once who always rocked this slouchy black leather blazer. She kept the sleeves at quarter length, wore painted on cigarette jeans, smoked Dunhills, and wrote the best papers in our Media Aesthetics class.
It was kind of like this blazer from Asos. Get your girl this one and you'll probably even get cooler by association.
Even though it isn't leather, I think this Parkside military style blazer is pretty cool. I totally wouldn't be bummed if my girl showed up with this on. Nasty Gal wins again with this pick.
If your girl already owns a jacket like this, marry her. Or at least propose. Although it's a double-edged sword. She might be so cool you'll feel inferior all the time...
Maybe you should try and get your girl sponsored by Nasty Gal. Then you wouldn't have to worry about it anymore.