I once used Goodreads, but it seems more live action role-playing and less reading, in addition to being a terrible user experience. Anyway, as the Haruki Murakami quote goes:

"If you only read the books that everyone else is reading, you can only think what everyone else is thinking."

Also, I finish maybe one in every ten books, which turns Goodreads into a chore and takes all the fun out of reading. Imagine the horror of seeing 43 books in the currently-reading section.

I don't like writing summaries/reviews, but plan to write them as much as possible. You can look at the books I read in a particular year and their summaries in the yearly links.
The main list is the books I have read, plan to read, or want to read in no particular order. The black/blue links are for read/not read titles respectively.
I have color coded my recommendations in red, and must-reads in red and bold.

I don't believe in 'formative' books. Nor do I think a book should strike two people with the same intensity.
That being said, some books are powerful enough to be formative. Always be skeptical, for books are excellent slaves but terrible masters.