These products are Webware editor's Rafe Needleman's somewhat secret productivity tools. Neither are well-known products, but both enable a person who does a lot of writing on more than one computer to stay productive.
Evernote is a note-taking application that has both downloadable software and a Web app. No matter which machine--PC, Mac, or iPhone--you use to take notes, you can see them almost immediately on any other of your machines that have the software. You can also get your notes on the Evernote Web service. Plus, the text of photos uploaded to the service is indexed, so you can search for labels and signs you've taken pictures of. Not only is Evernote a clever hybrid (software/Web) app, but it's a strong note-taking product, competitive with Microsoft's OneNote. The basic version of Evernote is free.
Microsoft's Windows Live Sync is a file sync tool. It lets you connect any Mac or Windows computer's directories together, so that any file saved or changed in one is automatically synchronized to the others. If you use more than one computer, this product is fantastically useful. It saves you from having to worry about where you store your files. They're all everywhere. And it's completely peer-to-peer, so unlike competitive file sync tools that store your files on Web servers (including Microsoft's own Mesh), there are not storage or bandwidth restrictions. And it's free.