Hi bettyalice, welcome to the forum.
There is nothing for Facebook like Topsy for Twitter at the moment.
What you can do on Facebook to discover interesting content is by subscribing to Pages that post high quality or shareable content that are relevant to the topic that you are looking for.
If you are looking for generic tips on how to get the most coverage for your posts, then you should have a look at the following blog posts:
7 Tips to Maximize Shares of Your Facebook Posts by Mari Smith
[INFOGRAPHIC] How to Get More Likes, Shares on Facebook by Samantha Murphy