If you use Gmail as your primary email, you might be receiving emails with attachments. The general process followed for these attachments is that you download them to desktop or open them using Google Docs. Gmail Attachments To Docs is a nice extension for Google Chrome which allows you to easily save all the documents directly from the email interface to your Google Docs account. Once installed, you can see an additional link against each attachment to save them to Google Docs.
When you click on the link, it opens a new tab where the document is uploaded to Google Docs. You get a confirmation on successful upload.
This is very useful if you use Google Docs as your online storage for all your documents.