Google Docs let you upload files from web addresses, but it's not a convenient option, particularly if you want to upload many documents or you want to add a link for uploading a document. Here's the direct link that can be used to open a document from the web in Google Docs. This works for documents (.doc/.txt/.html/.rtf/.odt), spreadsheets (.xls/.csv/.ods), presentations (.ppt) and PDF files.

http://docs.google.com/?action=updoc&formsubmitted=true&uploadURL=DOCUMENTURL

If you’re a Windows users, you can create a batch file to automate multiple files uploading to Google Docs. For example, the following text can be copied in Notepad and saved as a .bat file. After executing the .bat, the two PDF files will upload to Google Docs in separate Firefox tabs (assuming that the browser is open and you are already logged in to a Google Account.)

start /d "%PROGRAMFILES%\Mozilla Firefox" firefox "http://docs.google.com/?action=updoc&formsubmitted=true&uploadURL=http://www.fireworksafety.com/pdfs/FireworkSafetyTest.pdf"

start /d "%PROGRAMFILES%\Mozilla Firefox" firefox "http://docs.google.com/?action=updoc&formsubmitted=true&uploadURL=www.fs.fed.us/fire/safety/wct/2002/brochure_2002.pdf"

Source:→ Google System