Based on the Pure Reader mod for Google Reader we covered back in December, 3 Column Reader is a new Safari extension released in June and updated last week that enables you to turn the Google Reader website into a beautiful, three-column reading experience for your RSS feeds. Developed by Zackary Corbett, 3 Column Reader is only compatible with Safari for now, and it’s got a minor glitch with the settings icon from Google’s new sharing toolbar launched alongside the Plus social network. However, the extension is being actively developed so we wouldn’t be surprised to see a fix for users logged into Google+ soon.

For everything else, 3 Column Reader looks great: the extension takes Pure Reader’s color scheme (which reminds us of Reeder’s sepia background and monochrome icons) to lay out a three-column setup perfect for widescreen monitors: folders and feeds are listed on the left, a mid panel visualizes the feeds’ titles and excerpts, and the full articles with images are displayed on the right. You can hide the source list by hitting an icon in the mid panel, and most of Google Reader’s web app functionalities are retained, such as popup menus to sort articles, or buttons to mark items as favorite. I didn’t encounter any other compatibility issues when using 3 Column Reader on Safari 5.1 for Lion GM.

You can download 3 Column Reader here, and disable it at any time from Safari’s extensions page in the Preferences.

Update: the issues I reported with the Google settings icon have been fixed with an update, and the extension is now available for Google Chrome, too. Get the updated versions here.