Here are four good sources of info on batteries, the last two covering primarily NiCads.
The first one having very good info on all types of batteries.
http://www.rcbatteryclinic.com
http://www.whenshtf.com/showthread.php?t=2153
http://www.srbatteries.com/nimh.htm
http://dansdata.com/gz011.htm
http://users.frii.com/dlc/battery.htm