This is a very broad question, and one that keeps spawning smaller, related questions the longer I think about it. Personally, I rely on aggregators such as Hubski, Hacker News, and to an ever decreasing extent Reddit to find new content. But I almost never post to any of these sites because the majority of the content I enjoy was found on at least one of them and has already been reposted on the others. I imagine the people who post more often must either be very quick to share new discoveries or else spend a great deal of time combing through the miles of less interesting stuff. Then this morning, I read this post by goo and it made me wonder if it's just a personality difference.
Ultimately I strive to be a less passive member of Hubski, but I never want to post just for the sake of posting. But the obstacles to finding content worth sharing continue to mount. Mainly it's about a lack of time, and an aversion to being bombarded with ads.
So how do you find the content you share? And what motivates you to share it?