It´s true a blog will capture long tail traffic and help the e commerce site but would you go with a sub domain approach or sub folder I´ve been thinking lately a sub domain would work better especially because of panda penguin The idea of putting the NOINDEX tag is show the engines only your best content to keep up your batting average so speak Each site has a different trust ranking in the eyes of the engines, so some can get away with being poorly descriptive while others can´t.