Which is the best site to check for volumes/trends/contracts etc. during market hours.?
Your broker could give you a code / trading s/w which will be of help. talk to your broker. Otherwise you can also try http://in.finance.yahoo.com, sites by Bonanza :
http://contentlinks.asiancerc.com/Bestbull/derivatives.asp
Above will display the contracts and volume but its normally shows price with a delay of 30 minutes.
You need to create a portfolio in http://in.finance.yahoo.com. You can see day graphs as well. For example track Nifty trend during day time using graph.
Regards