Once Campaign goes live then measure the following to find the delta for before and after
Traffic Volumes, PPC conversions, referral numbers, effectiveness of keyword usage, time spent on sites, bounce rates
Levels of interaction
Comments left by users, number of Retweets, number of Fans on Facebook pages, numbers of @comments in twitter, number of subscribers through email and RSS
create measurable and trackable conversion points in your sales funnel – sign up for newsletter, make a purchase, click on a link, fill out contact form, download a trial version, whitepapers, attend webinars, podcasts listens, etc.
Search Engine Optimisation
links from blogs, trackbacks, comments left in blogs, views of embedded digital content that you provided, Digg links