Backpack is site for collaboration. You can create pages, and each page can have its own title, and can have Notes, Lists, and Writeboards.
Each page can be public or shared. In order to share privately, your collaborators must also register with Backpack. The site emails your contacts for you.
Each page you create gets a special email address you can use to email yourself a note, say if you are unable to use the web.
Writeboards are a great feature. Backpack's site supports tracking changes.
The Free account lets you have five pages, and does not support the calendar features. For that you have to upgrade to a paid account.
The main page is an enormous ad for the site's features, and it's difficult to find the link to log in, which is down the bottom in small type.
You can't change the default font or the page background color.
You can't change the page's special email address, even though you can generate a new one, but it's always random-name,number,email@example.com