I think the first order of importance is fully tracking what happens on your website, i.e., web analytics. That way, you can know the sources of traffic and how visitors of those sources behave once they arrive. This is where the rubber meets the road. The second order of importance is knowing how people talk about you online using social media. These online conversations directly impact people's awareness of your company and products. They also impact how search engines index your content as well as other content that mentions your brand and products.
Finally in my book come search analytics. Search analytics help you understand what terms are being searched for and in what contexts. Specifically, search analytics help you choose the terms you want to be known for.
I've ranked these items 1 to 3, but they are all important. If you only did one, it would be web analytics. However, social media and search analytics are so intertwined that you need to do both together. Follows a sample of tools that I see being routinely used. Feel free to use comments to suggest other tools or ways of seeing this.
- Google Analytics (free and paid)
- Omniture (paid)
- Google Webmaster Tools (free)
- Bing Webmaster Tools (free)
Social Media Analytics
- Social mention (free)
- Google discussion search (free)
- Facebook page insights (free)
- Google Analytics Multichannel funnels (free and paid)
- Sprout Social (paid)
- Moz (formerly SEOMoz, free and paid)
- Hubspot (paid)
- Omniture SocialAnalytics (paid)
- BrandWatch (paid)
- Salesforce Marketing Cloud (formerly Radian6 and Buddy Media, paid)