Sticky notes for the web! MyStickies let’s you put sticky notes on a
web page and loads them back up when you come back to the page.

To put it simply, Mystickies allows you to place little yellow squares
of digital paper anywhere and everywhere you feel like in the whole wide web.
Along with the ability to put sticky notes on webpages mystickies offers a
powerfull interface to browse, search, sort, edit and generally have a wonderfull
time with your sticky notes from any computer that has internet access.

Goodbye to Bookmarks?

Mystickies is like bookmarks on steroids. While bookmarks store the title
of a webpage and a link they do little to help you find what was important
about the page and why exactly you chose to mark it. Mystickies solves this
problem by giving you the power to mark up the page the way you like, and
a tool to find notes easily and efficiently.

More here.