So after this post I have been comparing the three options I had: Goodreads, LibraryThing and Shelfari (suggested by Miss-Informed). I have read so many reviews (review 1, review 2 and more). I finally decided to stick with LibraryThing because they have features like "Tags" and "suggestions/recommendations". Since this morning, I have been adding the books I have in office and I started to like it even more. I can also export my library to "CSV" or "tab-delimited" format and then import it into my other accounts at Goodreads and Shelfari (didn't try it yet).