Ooo2gd is an OpenOffice addon which you can use to keep your documents synchronized with Google Docs, Zoho and WebDAV servers. You can either manually select to upload a file to Google Docs / Zoho when you're done editing it or you can select to automatically synchronize it.
If you want to upload a lot of documents to Google Docs, it's difficult to upload them one by one. You can send the documents by email, but this option is not very reliable and not all the formats are supported.