Seattle-based Shelfari, which is now owned by Amazon.com, said this week that it has made a number of enhancements to its site. According to Shelfari, the firm has added new search capabilities to the site, including new expanded search fields and advanced search options, along with added a new header navigation features. Shelfari said that among its updates, it now allows users to search for books by keyword, subject, binding, publisher, language, and publish date, in addition to prior options for searching by author, title, or ISBN. Amazon.com bought Shelfari in August of last year; Shelfari was backed by Curious Office Partners and Amazon itself. The site offers social networking and ways to share reviews and opinions on book titles.