If your engaged in social media and other forms of digital communications, I think it is crucial to monitor and measure your efforts.
Google Analytics has been a powerful tool for my work at State and Federal Communications. It was worth the work to get the Google Analytics Individual Qualification. Google has great (and free) training resources here.
Social media measurement can be tricky. I gave a presentation at the Advanced Learning Institute in July 2011 about best practices for social media practitioners. As a rule, I try to work from the broader communications goals to find the right measurements and I try to connect social media marketing to results that happen in real life - leads, phone calls, brand positioning.