Insync is a Google Drive client for Mac, Windows and mobile devices that recently got support for Linux (beta).
Besides full sync support for Google's cloud storage service,
Google Drive, which includes Google documents (unlike
Grive) that it downloads as .doc, .xls, .ppt, etc., Insync for Linux also comes with
Nautilus integration, tray / Ubuntu AppIndicator support that displays recent changes, errors and the sync status and
support for multiple accounts.