We upgraded our http://zohosheet.com service couple of days back with some goodies like Multiple Sheets, AJAX, etc.
You can now have multiple sheets (as tabs at the bottom) in a single document (workbook). This is very useful for maintaining all related data in a single document. Your already imported spreadsheets will automatically show all the sheets now. You can insert / add / rename / delete sheets. You can also refer to a cell in another sheet in the document.
We have AJAX-fied the whole interface now. Loading a document / creating a new one is much smoother and faster now.
We have also created a Firefox extension to automatically go to Fullscreen mode whenever you visit zohosheet.com. Apart from that, we have done some fixes and enhancements.
Detailed information is available on our What’s New page.
We also acknowledge that some important features such as insert rows / columns are missing and we will be adding them in our next update.