Humyo provides an online storage and backup service for both businesses and personal users. All documents, spreadsheets,
presentations uploaded to Humyo can now be viewed, edited & saved back online using the Zoho API.
The below screenshot lists files in my Humyo account and right-clicking on a spreasheet file opens up a dialog as shown.
Clicking on the Open this document option will open the file in a new Zoho pop-up window, in this case Zoho Sheet's.
Likewise, documents (doc, odt etc) will get opened in Zoho Writer and presentations (ppt, pps, odp etc) in Zoho Show. The embedded video below by the Humyo team explains the functionality in detail.
Give Humyo a try.