Spreadsheet Application

• EditGrid 
• Expresso spreadsheet
• Google Docs
• Office Web Apps
• Sheetster
• Smartsheet
• ZCubes - Calci
• Zoho Office Suite

• Dhtmlx Spreadsheet
• Simple Spreadsheet
• Tiki Wiki CMS Groupware includes a spreadsheet since 2004 and migrated to jQuery.sheet in 2010.
• wikiCalc (now called SocialCalc)
• GelSheet
• EtherCalc

source : http://en.wikipedia.org/wiki/List_of_online_spreadsheets