This is a great question. I was only able to answer it once I figured out what kind of online persona I wanted. I opted for a Twitter feed and Facebook page that reflected who I am: a person with diverse interests and who believes in connecting and engaging people.
Like my friend Paul Steele, I am not in the business of telling people what kind of things people should post on their account. But since I get questions about how I find the content I post, I figured I would share a few things. I would divide my content up in 5 parts:
(1) Quotes and Affirmations - People like to feel good. Myself included. I will post quotes from the people I profiled in my piece 16 People on Twitter Who Inspire the World. But I also look for Cindy Ashton, Paul Harris, Elisa All, Aine Belton and so many others on my Twitter list called Daily Inspiration. Spreading positivity can never be oversold. Never.
(2) Random Facts - I love brain teasers, and information about things that make you say what?, really?, no way!, and just challenge your beliefs about topics. The OMGFacts feed does this better than most.
(3) Links - My first 4 months on Twitter were interesting. I posted a lot of articles from one feed, and most of it was on one topic. That was fine. But when I decided to post on various subjects and from various feeds, I felt that I had truly defined myself online. I started posting about food, the environment, technology, business, health and fitness, photography, charity and nonprofits, travel, etc. I look for dynamic feeds - whether 100 followers or 100,000 followers - that can enhance what I like to post.
(4) Music - I have some of the most diverse music taste out of anyone I know. I grew up listening to everything: rock, hip hop, jazz, classical, etc. So the music I post reflects that. I use Blip, though friends of mine like Lotay Yang and Emily Bratkovich use Grooveshark. There are many sites to choose from. The two I mentioned here are among the most popular.
(5) Engaging - This is probably my favorite part of social networking: being social, and actively engaging people. I say thank you. I recommend people in a particular person's field or city of residence. I provide more links if someone needs more understanding on something I tweeted. And of course, I retweet.
This is how my Twitter feed, and to some extent, my Facebook page, are put together. "Great Social Media Content" is not one style. Don't let anyone tell you that it is. Just figure out what you want to do in social media (positively speaking), and be the best at it. Make it happen!