I thought I felt a disturbance in the Force this morning. The source: Google. The search giant dropped an enormous bomb on me today: Sidewiki.

Sidewiki is a browser tool — it plugs in to Firefox or Internet Explorer (no Google Chrome support for a Google tool? How odd!). It allows you to write and read annotations to any Web site. Let me say that again: you can add content (or read content added by other people) to any site on the Web using this tool.

The additional information appears in a sidebar to the left of the body of the Web site (the tool shifts the rest of the site over to the right in a squished view). The data can include thoughts, comments and even active links to other Web sites. More on that later.

The only way you can read added material is to download the tool and activate it yourself while viewing a Web page. User-generated content won’t just pop up on the site on its own. But this tool could conceivably make a huge impact on the Web.