LibreOffice Calc is the spreadsheet program you've always needed. A fork of OpenOffice.org Calc, professional data miners and number crunchers will appreciate its comprehensive range of advanced functions.
EtherCalc is a web spreadsheet. Your data is saved on the web, and people can edit the same document at the same time. Everybody's changes are instantly reflected on all screens. Work together on inventories, survey forms, list management, brainstorming sessions and more!
Keikai is the only Web Spreadsheet designed and architected for big data — and is the fastest web spreadsheet regardless of size. Other advanced features include embeddable in your Web Apps, providing true Excel experiences and more.
SC-IM - Spreadsheet Calculator Improvised – An ncurses spreadsheet program for the terminal. - CSV / TAB delimited / XLSX file import and export. - Scripting support with LUA. Also with triggers and c dynamic linked modules. - Clipboard support. - GNUPlot interaction.
wikiCalc is a wiki-based spreadsheet developed by Dan Bricklin and released under a GPL license. SocialCalc is co-developed with Dan and Socialtext, released under SPL and is being integrated with Socialtext Open.