Check out what's in these categories:
http://www.wowinterface.com/downloads/cat20.html and
http://www.wowinterface.com/downloads/cat78.html
There are plenty of addons that do what you describe, some in each location. I personally use ReagentRestocker, though it does more than just what you are asking.
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"You'd be surprised how many people violate this simple principle every day of their lives and try to fit square pegs into round holes, ignoring the clear reality that Things Are As They Are." -Benjamin Hoff,
The Tao of Pooh