BTC-E
exchange URL: https://btc-e.com/api/2/btc_usd/ticker
exhange rate JSON key: sell
field 1 JSON key: sell
field 2 JSON key: last
field 3 JSON key: buy

Vircurex
exchange URL: https://vircurex.com/api/get_info_for_1_currency.json?base=BTC&alt=USD
exhange rate JSON key: lowest_ask
field 1 JSON key: lowest_ask
field 2 JSON key: last_trade
field 3 JSON key: highest_bid

Bitstamp
exchange URL: https://www.bitstamp.net/api/ticker/
exhange rate JSON key: lowest_ask
field 1 JSON key: ask
field 2 JSON key: last
field 3 JSON key: bid