If you are tall and thin, look for a slouchy, rounded hobo bag to compliment your figure.
If you're short and voluptous, play off opposites by choosing a handbag that is tall and rectangular or long and sleek (like a clutch). In general, the rounder your figure, the more structured your bag should be.
Great selection of handbags are available at
Handbags from Zappos.com 
They are known for shoes, but have a great selection of handbags. its worth checking out.
Anyway, finding the right handbag doesn't mean that you have to carry a hard box around to counterbalance your womanly shape: rectangular or square silhouettes in soft leathers or fabrics will do the trick.
If you are feeling a little PRADA or feeling a little splurge coming on- take a peek! Theres FENDI, ARMANI, BALENCIAGA and lots more.

Some popular shapes:
Hobo bag - A crescent-shaped shoulder bag.
Tote - An open-top bag with straps or handles.
Duffle - Tall shoulderbag, often with a wider opening on top.
Field bag - A flap-top shoulderbag with utility-type closure (buckles, snaps, etc).
Clutch - A small, handheld bag or a larger, geometric shape that is tucked under the arm.
Satchel- A large, handheld bag.
Baguette - Long and rounded shoulder bag resembling the namesake bread.
Messenger - A large, soft shoulder bag with long straps (often worn across the body).
Cigar Box - A small, boxy, hard bag.
Pouch - A soft, small bag.
Kelly bag - A classic Hermes style named after Grace Kelly; a large, structured handbag with distinctive hardware closures.
Think scale here: a woman who is 6 feet tall and a size 14 would look lost with a teensy hand-held bag. A petite size 0 would look overwhelmed by an enormous slouchy bag. A shoulder bag's length (where the bottom of the bag hits your body) will accentuate whatever part of the body it comes near. For example, a shoulder bag that ends around the hips will play up your hip width (the eye is drawn to the bag). Most women look great with a bag that hits mid-torso because it flatters the waist.