I am...

... A Bar Code Reader!!!

You are a highly competent individual who has societal value whereever you go -- whether you are in the busy stores of Madison Avenue or the outposts of Burkina Faso, your ability to decipher the indecipherable brings praise and jealousy.
While some are put off by your occasional beeping, most find it subtly soothing. Do not be afraid to assert yourself -- your timidity is by no means an asset. To achieve success, however, never leave the philosophy of simple math that got you where you are today: the checkout counter.

PS - I was serious about being assertive: that skirt really is 30% off!!!