I've been thinking that it would be nice to have one place where you can get trade data and aggregated trade data for all bitcoin exchanges, instead of having to work with the api's of each one.
Do you think there's a need for this, and from whom?
Check out XChange [0] for starters. It is a Java meta-API for various exchanges and written quite nicely. I personally use it for building a bot with a friend to look for arbitrage opportunities among the exchanges. Others use it as a mean price aggregator, to conduct trades on their own UI, or use historical data to backtest trading strategies.
[0] https://github.com/timmolter/XChange