Fleck has officially launched (November 16, 2006) to allow users to attach post-it like notes to any web site. Fleck is a privately funded company, founded by Boris Veldhuijzen van Zanten, Patrick de Laive and Arjen Schat. I first heard about Fleck back in March of 2006 as I reached out to Boris and found that they were in stealth mode. Taking a page out of Diddy's book, the Fleck team was at the TechCrunch 8 event at the posh NY nightclub BED dressed in white suits. If you signed one of their suits you were granted a free premium Fleck account.
Fleck introduces a toolbar that overlays the webpage. The toolbar enables users to annonate a web page with notes and expandable bullets. You can then share this page via email or by posting a link to your blog (Fleck is working on integrated with most blog platforms). Fleck also keeps track of annotation metrics and displays them on the site similar to how some social bookmarking sites display the most popular saved links. By saving a Fleck page that has been updated with notes a user can access them again later via a new Fleck URL. Fleck has a history feature which allows users to revert back to different saved views.
Above is a screen-shot of a page I annotated while Fleck was in beta. I enjoyed exploring the various features as Fleck has created a product with unique web interactivity.
UPDATE: TechCrunch has also reviewed Fleck.