"The SWFX Sentiment Index can be a valuable tool for intraday currency trading. The Index is based on transaction flow information and is designed to show long and short ratio in the most popular currencies and currency pairs consolidated by liquidity consumers and providers.
Liquidity providers are participants of SWFX marketplace represented by centralized marketplaces and a number of banks which continuously provide ask and bid prices on the market. The sentiment ratio of this group is opposite to liquidity consumers’ data because, for each trade executed through SWFX, there are two equal and offsetting over-the-counter transactions."
Knowledge of market depth via volumes is also invaluable.
Here's the link: http://www.dukascopy.com/plugins/fxMarketWatch/