I’m an Online/Digital PR person– but in the long run this description only generates the same questions as saying I’m a Social Media Strategist.
I think this pretty much sums it up: 
http://dailyinfographic.com/the-hectic-life-of-a-social-media-manager-infographic 
After setting up the proper digital and social media channels, I strategize how to use them as tools to achieve things like:
-Making sure we have a strong online presence
-Engaging with our online community
-Providing our current customers with fantastic customer service
-Listening to our customers to see what they think could improve
-Looking for opportunities with new customers
-Listening to our competitors’ customers to identify the mistakes our competitors are making – to make sure we don’t go down the same path.
-Listening to our own communities and restructuring our own online efforts to ‘keep the conversation going’

I have to make sure this is done everyday, and that the strategy never gets off track, or see if it needs adjusting to meet customers’ needs.