Right after I posted my last entry, about the Web annotation service Diigo, I got a demo of Posticky, another online "Post-it" service. This site isn't what I expected, though. It doesn't let you attach notes to Web pages. Instead, it's more like a bulletin board. You can create Post-it-type notes on your personal Posticky page on the site, and you can share the notes with others and view them on a mobile phone using a special mobile version of the site.
Posticky would be more useful if your notes were available in places other than the Posticky site. And you can't see your notes when you're offline. But it is a handy place to jot notes to yourself that you can later retrieve from any Web-enabled device. If that's what you need.