Thanks stockplaya, I'm just using Interactive Brokers Trader...

Thanks stockplaya, I'm just using Interactive Brokers Trader Workstation. Probably the most useful feature is the volume histogram which shows cumulative volume at different price levels. I think this is included in lots of charting software so nothing special really. However, the way I use the cumulative volume is really just to spot potential intraday turning points, so it is most useful in situations such as when a lot of volume is trapped above e.g. from Friday, and the price moves quickly and significantly lower (even better if it gaps down) e.g. today, which results in a large supply vacuum beneath the high cumulative volume. Often the price will then move quickly back through this vacuum before smacking into the high volume zones above where lots of punters are trapped above and want to bail after seeing the scary down move :) So all I look for is some bullish action at the bottom of the vacuum, then jump in and ride it up to the high volume zone. Hope that makes sense.