If your site doesn’t allow comments on articles or other types of content yet, don’t worry. Facebook is coming to the rescue. A new in-house built widget, called Comments Box, allows Facebook users to login through Facebook Connect and leave comments on a website with their name and profile picture from Facebook.

Facebook says it’s a quick and easy way for Web sites to add social features without developing or managing custom plug-ins.

Any comment posted in the Comments Box will also appear on the user’s Facebook Wall. Non-users can post comments using the widget, too.

The new service should make Facebook even more ubiquitous. As if the company needed that.