I've just released the first version of a new API for interacting with Bitcoin exchanges for node.js. I've been using it for a couple weeks now and it seems to work pretty well, but no guarantees.

Goal:
The purpose of this project is to provide a robust enough interface to interact
with Bitcoin exchanges (in whatever way that might be) without going into things
that necessarily should be customized such as trading bot strategies.

Current Features:

• Mostly written for compatibility with Mt Gox API
• Known to work with: Mt Gox, TradeHill, Bitcoin7 (via ExchangeB7 class), ExchangeBitcoins
• Check Account Balance in USD and BTC
• Place Buy and Sell Orders
• Find out the cost (USD) to buy a given amount of BTCs (including trade fee) on an exchange
• Find out the gain in selling a given amount of BTCs (including trade fee) on an exchange

Install:

Source:
https://github.com/freewil/btc-ex-api