The Accumulation Distribution Indicator tracks the relationship between price and volume, acting as a leading indicator of price movements. The strongest signals are divergences.
Richard W Arms' powerful Ease of Movement indicator highlights the relationship between volume and price changes; useful for assessing the strength of a trend.
Colin Twiggs' Money Flow is a derivation of the Chaikin Money Flow indicator. Position above/below the zero line gives advance indication of breakouts, while divergences warn of reversals.
Williams Accumulation Distribution is traded on divergences. When price makes a new high and the indicator fails to exceed its previous high, distribution is taking place.