Corsets.
These are amazing, expecially for pear-shapes with little boob (I'm in the same boat). They'll hoik them up to about chin height, so top-heavyness appears to come from boobs, not broadness. Also, you'll get a slimmer waist, that WILL turn heads, and drive attention away from shoulders. A proper one won't hurt, only a badly-made ill-fitting one; you'll get good posture to boot.
If you want one, I do advise you get one tailor-made, but be warned, this can be expensive, so if you do want one, save up. And don't be tempted by the cheap mass-produced ones as they're a waste of money.
Away from corsets, I would advise to avoid anything attention-grabbing up top, and save it for lower down (eg belts). If you like skirts, get a poofy one that finishes about knee to mid-calf, it'll balance you out, and showing slim legs will help avoid looking like a blimp (as I would, because I'm not blessed with slim calves ^^; )