Backpack: A personal productivity web application
I have just started using Backpack, a personal productivity application that is kind of like a cross between a wiki and a blog.
You can create pages (up to 5 on the free account), and then to each page you can add content, lists, notes images and files. There is also a reminders page, where you can set up reminders that can be either emailed to you or sent to your mobile phone (if you provider is supported). You can also email list items, notes, images and files to the page from anywhere.
As far as content management goes, it is fairly unstructured - you can put just about whatever you want on a page. Each page is really just a place where you can collect together a whole lot of bits of information about a particular topic.
There is also the option to share the page with other people (either specified people or the general public). This could be useful for things like planning a group event or a group trip. Of course, you could easily make your own page to do that, but this just makes it so much easier - no need for html editing applications, uploading or mastering cryptic tags.
The thing that sets this apart from a blog is that it seems a little more personal. Blog entries need to have some sort of structure and purpose, whereas you can use Backpack to just keep track of random thoughts, snippets of information for later personal use. It also doesn't have the permanence of a wiki, making it seem lightweight and easy to use.
Of course, 37 Signals have done a fantastic job of using the "Ajax" technology, even with apparently quite high load on their server early on, it is really fast and easy to use.
I've set Backpack as my homepage, but I'll have to wait and see whether I really am inclined to use it rather than use a Notepad file or scribble on the back of one of my old business cards.