According to an article in 'Chief Marketer' (based on a survey from the CMO Council) one need tops them all--Analytics!

When asked their most urgent developmental priority, over half said it was to improve their marketing analytics capability.

Although term 'analytics' can be very general to include both online and offline measurement it's not a stretch to consider that web analytics has to be critical for any marketer with a serious online effort.

One speaker at the recent Webmaster World pub conference in Las Vegas commented that web analytics has a long way to go, however, to achieving critical mass. He noted that of all businesses doing over $1,000,000 in annual revenues, and who have a website, only 17% are actually measuring website activity with analytics. That figure is astounding!