In general, it looks like when the markets are going down, the volume picks up.

[link|http://finance.yahoo.com/q?s=^DJI&d=c&k=c1&a=v&p=s&t=1y&l=off&z=m&q=l|Dow]

[link|http://finance.yahoo.com/q?s=^IXIC&d=c&k=c1&a=v&p=s&t=5y&l=off&z=m&q=l|NASDAQ]