I have written a Python program that looks at bitcoinchart's API and finds the median price. This might be useful if you wanted to automatically adjust prices in an online store.

import urllib2
import json

def average(l):
    return sum(l)/float(len(l))
#From fraxel
def median(mylist):
    sorts = sorted(mylist)
    length = len(sorts)
    if not length % 2:
        return (sorts[length / 2] + sorts[length / 2 - 1]) / 2.0
    return sorts[length / 2]

currency = "USD"
url = "http://api.bitcoincharts.com/v1/markets.json"
result = urllib2.urlopen(url).read()
prices = json.loads(result)


def by_currency(symbol):
    def f(ticker):
        return ticker['currency'] == symbol
    return f
def by_volume(min_volume):
    def f(ticker):
        return ticker['currency_volume'] > min_volume
    return f
def get_price(ticker):
    try:
        return average((ticker['ask'], ticker['bid']))
    except:
        pass
    print ticker
    raise Exception("Can't find price in ticker")

# Avoid prices in wrong currencies
prices = filter(by_currency(currency), prices)
# Exclude small exchanges
prices = filter(by_volume(100), prices)
prices = map(get_price, prices)


single_price = median(prices)
print single_price