Make a streamlined tail box trunk you can mount on the rack. Or Cervelo S5-like tube shapes you can mount over your round tubes (and pay attention to the joints, it's cool the way they did those). Airfoil instrument panel if you put stuff on your handlebar, or how about clip-on aerobars? Maybe something more mundane like quick-mount fenders and maybe a chain/ring cover. Or, personally, I'd jump at the chance to 3-d print my front fairing but that's a whole nuther can of worms ...