I always feel one of the joys of reading is that it is a quiet solitary activity. It can be a chance to reflect and to escape into another world. Still it can be a lot of fun to share your reading experiences with other people. The following list are online tools and social media outlets for sharing what you are reading and to learn what others are learning.
First there's the really fun #fridayreads hashtag on Twitter. You simply post whatever you are reading on Friday with the hashtag #fridayreads. You can then search the hashtag and see what other people are reading too. You can find out more on their website. You can also join their Facebook page.
You can get involved with the community at GoodReads. There you can post what you've already read, what you are reading at any given time and how far along you are in the book, and what you would like to read. You can also follow friends and authors. There are online book clubs, book recommendations, and book lists. There is also Shelfari and LibraryThing. They each have a slightly different focus, but they do encourage communities of book lovers.
There are also online groups and projects that you can participate in. One example is Book Drum, an interactive crowd-sourced literary world map. Another fun project is BookCrossing. Basically you register and label a book you own through their website. Then you share the book by giving it to someone or leaving it somewhere. After that you can follow the book as it gets passed along. You could also participate in World Book Night in April. In this program 30 books are chosen every year. Then people can sign up to personally hand out 20 copies of a particular title in their community. The goal is to hand out books to people who are either light or non-readers.
There are a lot of great book blogs that you can follow and comment on. Here are some recommendations: The Book Lady's Blog, Omnivoracious, Three Guys One Book, and Book Riot (my personal favorite). You can also look to see if your favorite author maintains a blog. For example, John Green actively engages with his readers on his website.
Here's an interesting article about Facebook Apps that you might want to check out.
These book tools are less about sharing what you read and more about receiving suggestions on other things to read: Book Lamp, 5 Websites That Alert Book Lovers About New Book Releases, and Reading suggestion engines: Your next read.
I hope this post has given you some inspiration on how to read socially! Happy reading!