Opera Software ASA Tuesday unveiled the Opera 9 Web browser, which offers new features such as thumbnail preview panes, a built-in content blocker, integrated BitTorrent peer-to-peer file distribution and transfer capabilities, and "widgets" -- small Web applications such as multimedia add-ons, newsfeeds, games and more that can be used to customize a user's desktop.

The new browser can be downloaded free of charge at Opera.com. It comes in versions for Windows, Mac OS X, Linux and other operating systems, and it's available in more than 25 languages.

"For Opera 9, we worked hard to push the limits of what people expect from a Web browser, with increased speed, new Web standards support and innovative features such as widgets and BitTorrent," Jon S von Tetzchner, CEO of Opera, said in a statement. "Even though we shaped this browser for the Web's future, we have the powerful features people want and need for their surfing today. I truly feel Opera 9 has something for everyone."

The latest version also allows a user to select the search engine to be used for integrated search and offers improvements on Opera's tabbed browser features. Users can also save their browser sessions, so they can stop a session, close Opera and resume Web-surfing where they left off when they reopen the browser.

The latest version also includes a new security bar to help prevent phishing and other online scams, as well as new button options and "skins" for customizing the browser's appearance.

Opera 9 supports open standards and includes tools to make it easier for Web developers to code their sites for the open standards, including built-in Extensible Rendering Architecture to help developers confirm that their sites work well on any Web-connected device, according to the Oslo, Norway-based company.