Note that these methods can be applied with all documents that are supported by Google Docs, except in some cases where PDF or other formats are not supported.
Method 1 – Google Docs Sidebar Gadget
This method is by far the most easiest and quickest if you are already using Google Desktop Sidebar. It is cross-platform so you don’t have to worry which OS you are using.
Method 2 – DocList Uploader
This tool has been developed by Google to show off their API. It is a simple tool for Windows that allows users to quickly drag & drop their documents and they will be uploaded to Google Docs. It also adds option to the explorer right-click context menu which allows quick uploading of supported documents.
Method 3 – Google’s Firefox Toolbar
The latest version of Google Toolbar for Firefox allows users to upload documents and spreadsheets directly to Google Docs. Just you need to drag the document files and drop them to Firefox. You will have to enable this feature by going to Toolbar options before using it.
Method 4 – Google Docs Batch Upload
The above methods have some limitations, they support limited document formats. Luckily Google Docs Batch Upload is a command line tool from Google that allows users to batch upload all supported documents. Which means you can upload PDF documents along with spreadsheets, presentations, and word documents.
Method 5 – Drag and Drop
If you have the latest version of Google Chrome or Mozilla Firefox you can drag and drop files directly into your Google account document list or directly into a collection.
Method 6 – Google Cloud Connect
Google Cloud Connect is a free cloud computing plug-in for Windows Microsoft Office 2003, 2007 and 2010 that can automatically store and synchronize any Microsoft Word document, PowerPoint presentation, or Excel spreadsheet to Google Docs in Google Docs or Microsoft Office formats.
See simpler file uploads in Google docs blog from Google: http://googledocs.blogspot.com/2011/04/simpler-file-upload-in-google-docs.html
Also see Drag and Drop uploads and compact controls blog from Google: http://googledocs.blogspot.com/2010/11/new-this-week-in-docs-drag-and-drop.html