Here’s a tool that fits one specific niche, but fits it well: GDocsUploader. It only works on Mac OS X, and only helps out if you’ve got documents on your desktop that you want to move to Google Documents. But if that describes you, it’s worth grabbing and installing the tiny download. After you do, you’ll have an icon on your desktop (or wherever you choose to put it) that is a simple pipeline to Google.
Drag and drop a document on the icon, and GDocsUploader will pipe it over to your Google Documents account. After the first use, your credentials are stored in your keychain. After the upload, it can pop open a browser window for you. Of course, you could just open the Google Documents site and use the Upload link, but depending on how you work, this app can save you a tiny bit of friction. And that’s always good.